ELECTRICITY  FOR  THE  FARM 


THE  MACMILLAN  COMPANY 

HEW  YORK   •  BOSTON   •   CHICAGO   •  DALLAS 
ATLANTA   •   SAN  FRANCISCO 

MACMILLAN  &  CO.,  LIMITED 

LONDON   •  BOMBAY   •  CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  LTD. 

TORONTO 


ELECTRICITY    FOR 
THE  FARM 


LIGHT,  HEAT  AND  POWER  BY  INEXPENSIVE 

METHODS    FROM    THE    WATER 

WHEEL  OR  FARM  ENGINE 


BY 
FREDERICK  IRVING  ANDERSON 

AUTHOR  OP  "  THE  FABMEB  OP  TO-MOBBOW,"  ETC.,  BTC. 


fork 
THE  MACMILLAN  COMPANY 

1916 

AU  rieht*  reserved 


COPYBIQHT,  1915 

BY  THE  CURTIS  PUBLISHING  COMPANY 
The  Country  Gentleman 

COPYRIGHT,  1915 

BY  THE  MACMILLAN  COMPANY 
Set  up  and  electrotyped.     Published  April,  1915.    Reprinted 
December,  1916 


PREFACE 

» 

THIS  book  is  designed  primarily  to  give 
the  farmer  a  practical  working  knowledge  of 
electricity  for  use  as  light,  heat,  and  power  on 
the  farm.  The  electric  generator,  the  dynamo, 
is  explained  in  detail;  and  there  are  chapters 
on  electric  transmission  and  house-wiring,  by 
which  the  farm  mechanic  is  enabled  to  install 
his  own  plant  without  the  aid  and  expense 
of  an  expert. 

With  modern  appliances,  within  the  means 
of  the  average  farmer,  the  generation  of  elec- 
tricity, with  its  unique  conveniences,  becomes 
automatic,  provided  some  dependable  source 
of  power  is  to  be  had — such  as  a  water  wheel, 
gasoline  (or  other  form  of  internal  combustion) 
engine,  or  the  ordinary  windmill.  The  water 
wheel  is  the  ideal  prime  mover  for  the  dynamo 
in  isolated  plants.  Since  water-power  is  run- 
ning to  waste  on  tens  of  thousands  of  our 


451825 


vi  PREFACE 

farms  throughout  the  country,  several  chap- 
ters are  devoted  to  this  phase  of  the  subject: 
these  include  descriptions  and  working  di- 
agrams of  weirs  and  other  simple  devices  for 
measuring  the  flow  of  streams;  there  are 
tables  and  formulas  by  which  any  one,  with 
a  knowledge  of  simple  arithmetic,  may  deter- 
mine the  power  to  be  had  from  falling  water 
under  given  conditions;  and  in  addition,  there 
are  diagrams  showing  in  general  the  method 
of  construction  of  dams,  bulkheads,  races, 
flumes,  etc.,  from  materials  usually  to  be 
found  on  a  farm.  The  tiny  unconsidered 
brook  that  waters  the  farm  pasture  frequently 
possesses  power  enough  to  supply  the  farm- 
stead with  clean,  cool,  safe  light  in  place  of 
the  dangerous,  inconvenient  oil  lamp;  a  small 
stream  capable  of  developing  from  twenty- 
five  to  fifty  horsepower  will  supply  a  farmer 
(at  practically  no  expense  beyond  the  original 
cost  of  installation)  not  only  with  light,  but 
with  power  for  even  the  heavier  farm  opera- 
tions, as  threshing;  and  in  addition  will  do 
the  washing,  ironing,  and  cooking,  and  at  the 


PREFACE  vii 

same  time  keep  the  house  warm  in  the  coldest 
weather.  Less  than  one  horsepower  of  energy 
will  light  the  farmstead;  less  than  five  horse- 
power of  energy  will  provide  light  and  small 
*  power,  and  take  the  drudgery  out  of  the 
kitchen. 

For  those  not  fortunate  enough  to  possess 
water-power  which  can  be  developed,  there  are 
chapters  on  the  use  of  the  farm  gasoline  engine 
and  windmill,  in  connection  with  the  modern 
storage  battery,  as  sources  of  electric  cur- 
rent. 

It  is  desired  to  make  acknowledgment  for 
illustrations  and  assistance  in  gathering  mate- 
rial for  the  book,  to  the  editors  of  The  Country 
Gentleman,  Philadelphia,  Pa.;  The  Crocker- 
Wheeler  Company,  Ampere,  N.  J.;  The 
General  Electric  Company,  Schenectady, 
N.  Y.;  the  Weston  Electrical  Instrument 
Company,  of  Newark,  N.  J.;  The  Chase 
Turbine  Manufacturing  Company,  Orange, 
Mass.;  the  C.  P.  Bradway  Machine  Works, 
West  Stafford,  Conn.;  The  Pelton  Water 
Wheel  Company,  San  Francisco  and  New 


viii  PREFACE 

York;  the  Ward  Leonard  Manufacturing 
Company,  Bronxville,  N.  Y.;  The  Fairbanks, 
Morse  Company,  Chicago;  and  the  Fitz  Water 
Wheel  Company,  Hanover,  Pa. 


TABLE  OF  CONTENTS 

PAGE 
INTRODUCTION XVU 

PART  I 
WATER-POWER 

CHAPTER  I 

A  WORKING  PLANT 

The  "agriculturist " — An  old  chair  factory —  A  neighbor's 
home-coming —  The  idle  wheel  in  commission  again 
— Light,  heat  and  power  for  nothing —  Advantages 
of  electricity 3 

CHAPTER  H 

A   LITTLE   PROSPECTING 

Small  amount  of  water  required  for  an  electric  plant — 
Exploring,  on  a  dull  day — A  rough  and  ready  weir 
— What  a  little  water  will  do — The  water  wheel 
and  the  dynamo — Electricity  consumed  the  instant 
it  is  produced — The  price  of  the  average  small 
plant,  not  counting  labor 22 

CHAPTER  m 

HOW  TO  MEASURE  WATER-POWER 

What  is  a  horsepower? — How  the  Carthaginians  manu- 
factured horsepower — All  that  goes  up  must  come 
ix 


x  TABLE  OF  CONTENTS 

PAGE 

down — How  the  sun  lifts  water  up  for  us  to  use — 
Water  the  ideal  power  for  generating  electricity — 
— The  weir — Table  for  estimating  flow  of  streams 
with  a  weir — Another  method  of  measuring — Fig- 
uring water  horsepower — The  size  of  the  wheel — 
What  head  is  required — Quantity  of  water  neces- 
sary   32 

CHAPTER  IV 

THE  WATER  WHEEL  AND  HOW  TO   INSTALL  IT 

Different  types  of  water  wheels — The  impulse  and  the 
reaction  wheels — The  impulse  wheel  adapted  to 
high  heads  and  small  amount  of  water — Pipe  lines — 
Table  of  resistance  in  pipes — Advantages  and  dis- 
advantages of  the  impulse  wheel — Other  forms 
of  impulse  wheels — The  reaction  turbine,  suited  to 
low  heads  and  large  quantity  of  water — Its  advan- 
tages and  limitations — Developing  a  water-power 
project:  the  dam;  the  race;  the  flume;  the  penstock; 
and  the  tailrace — Water  rights  for  the  farmer 56 

PART  II 
ELECTRICITY 

CHAPTER  V 
THE  DYNAMO;  WHAT  rr  DOES,  AND  HOW 

Electricity  compared  to  the  heat  and  light  of  the  sun — 
The  simple  dynamo — The  amount  of  electric  energy 
a  dynamo  will  generate — The  modern  dynamo — 
Measuring  power  in  terms  of  electricity — The  volt — 
The  ampere — The  ohm — The  watt  and  the  kilo- 


TABLE  OF  CONTENTS  xi 

PAGE 

watt  —  Ohm's  Law  of  the  electric  circuit,  and  some 
examples  of  its  application  —  Direct  current,  and 
alternating  current  —  Three  typjes  of  direct-current 
dynamos  :  series,  shunt,  and  compound  ............  89 

CHAPTER  VI 

WHAT   SIZE   PLANT   TO   INSTALL 

The  farmer's  wife  his  partner  —  Little  and  big  plants  — 
Limiting  factors  —  Fluctuations  in  water  supply  — 
The  average  plant  —  The  actual  plant  —  Amount 
of  current  required  for  various  operations  —  Standard 
voltage  —  A  specimen  allowance  for  electric  light  — 
Heating  and  cooking  by  electricity  —  Electric  power: 
the  electric  motor  ..............................  121 

CHAPTER  VH 

TRANSMISSION   LINES 

Copper  wire  —  Setting  of  poles  —  Loss  of  power  hi  trans- 
mission —  Ohm's  Law  and  examples  of  how  it  is 
used  in  figuring  size  of  wire  —  Copper-  wire  tables  — 
Examples  of  transmission  lines  —  When  to  use  high 
voltages  —  Over-compounding  a  dynamo  to  overcome 
transmission  loss  ..............................  153 


CHAPTER 

WIRING   THE  HOUSE 

The  insurance  code  —  Different  kinds  of  wiring  described 
—  Wooden  moulding  cheap  and  effective  —  The  dis- 
tributing panel  —  Branch  circuits  —  Protecting  the 
circuits  —  The  use  of  porcelain  tubes  and  other  in- 


xii  TABLE  OF  CONTENTS 

PAGE 

sulating  devices — Putting  up  chandeliers  and  wall- 
brackets — "Multiple"  connections — How  to  connect 
a  wall  switch — Special  wiring  required  for  heat  and 
power  circuits — Knob  and  cleat  wiring,  its  advan- 
tages and  disadvantages 172 

CHAPTER  IX 

THE  ELECTRIC   PLANT  AT   WORK 

Direct-connected  generating  sets — Belt  drive — The 
switchboard — Governors  and  voltage  regulators — 
Methods  of  achieving  constant  pressure  at  all  loads : 
Over-compounding  the  dynamo;  A  system  of  re- 
sistances (a  home-made  electric  radiator) ;  Regulat- 
ing voltage  by  means  of  the  rheostat — Automatic 
devices — Putting  the  plant  in  operation 192 

PART  III 

GASOLINE  ENGINES,  WINDMILLS,  ETC. 
THE  STORAGE  BATTERIES 

CHAPTER  X 

GASOLINE   ENGINE   PLANTS 

The  standard  voltage  set — Two-cycle  and  four-cycle 
gasoline  engines — Horsepower,  and  fuel  consump- 
tion— Efficiency  of  small  engines  and  generators — 
Cost  of  operating  a  one-kilowatt  plant 217 

CHAPTER  XI 

THE   STORAGE   BATTERY 

What  a  storage  battery  does — The  lead  battery  and  the 
Edison  battery — Economy  of  tungsten  lamps  for 


TABLE  OF  CONTENTS  riii 

PAGE 

storage  batteries — The  low-voltage  battery  for 
electric  light — How  to  figure  the  capacity  of  a  bat- 
tery— Table  of  light  requirements  for  a  farm  house — 
Watt-hours  and  lamp-hours — The  cost  of  storage 
battery  current — How  to  charge  a  storage  battery — 
Care  of  storage  batteries 229 

CHAPTER  XH 

BATTERY  CHARGING   DEVICES 

The  automatic  plant  most  desirable — How  an  automobile 
lighting  and  starting  system  works — How  the  same 
results  can  be  achieved  in  house  lighting,  by  means 
of  automatic  devices — Plants  without  automatic 
regulation — Care  necessary — The  use  of  heating  de- 
vices on  storage  battery  current — Portable  batteries 
— An  electricity  "route" — Automobile  power  for 
lighting  a  few  lamps 250 


ILLUSTRATIONS 

Even  the  tiny  trout  brook  becomes  a  thing  of  utility  as 

well  as  of  joy  Frontispiece 

Facing  page 
Farm  labor  and  materials  built  this  crib  and  stone  dam  . .     17 

Measuring  a  small  stream  with  a  weir 23 

Efficient  modern  adaptations  of  the  archaic  undershot 

and  overshot  water  wheels 59 

A  direct-current  dynamo  or  motor,  showing  details  of 

construction 92 

Details  of  voltmeter  or  ammeter 128 

Instantaneous  photograph  of  high-pressure  water  jet  be- 
ing quenched  by  buckets  of  a  tangential  wheel  ....  194 

A  tangential  wheel,  and  a  dynamo  keyed  to  the  same 

shaft — the  ideal  method  for  generating  electricity .  .  194 

A  rough-and-ready  farm  electric  plant,  supplying  two 
farms  with  light,  heat  and  power;  and  a  Ward 
Leonard-type  circuit  breaker  for  charging  storage 
batteries . .  .  244 


INTRODUCTION 

THE  sight  of  a  dozen  or  so  fat  young  horses 
and  mares  feeding  and  frolicking  on  the  wild 
range  of  the  Southwest  would  probably  in- 
spire the  average  farmer  as  an  awful  example 
of  horsepower  running  to  waste.  If,  by  some 
miracle,  he  came  on  such  a  sight  in  his  own 
pastures,  he  would  probably  consume  much 
time  practising  the  impossible  art  of  "creas- 
ing" the  wild  creatures  with  a  rifle  bullet- 
after  the  style  of  Kit  Carson  and  other  free 
rovers  of  the  old  prairies  when  they  were  in 
need  of  a  new  mount.  He  would  probably 
spend  uncounted  hours  behind  the  barn 
learning  to  throw  a  lariat;  and  one  fine  day 
he  would  sally  forth  to  capture  a  horsepower 
or  two — and,  once  captured,  he  would  use 
strength  and  strategy  breaking  the  wild  beast 
to  harness.  A  single  horsepower — animal — 
will  do  the  work  of  lifting  23,000  pounds  one 
foot  in  one  minute,  providing  the  animal  is 


rvu 


xviii  INTRODUCTION 

young,  and  sound,  and  is  fed  12  quarts  of  oats 
and  10  or  15  pounds  of  hay  a  day,  and  is  given 
a  chance  to  rest  16  hours  out  of  24 — providing 
also  it  has  a  dentist  to  take  care  of  its  teeth 
occasionally,  and  a  blacksmith  chiropodist  to 
keep  it  in  shoes.  On  the  hoof,  this  horsepower 
is  worth  about  $200 — unless  the  farmer  is 
looking  for  something  fancy  in  the  way  of 
drafters,  when  he  will  have  to  go  as  high  as 
$400  for  a  big  fellow.  And  after  10  or  15 
years,  the  farmer  would  look  around  for 
another  horse,  because  an  animal  grows  old. 

This  animal  horsepower  isn't  a  very  efficient 
horsepower.  In  fact,  it  is  less  than  three- 
fourths  of  an  actual  horsepower,  as  engineers 
use  the  term.  A  real  horsepower  will  do  the 
work  of  lifting  33,000  pounds  one  foot  in  one 
minute — or  550  pounds  one  foot  in  one  second. 
Burn  a  pint  of  gasoline,  with  14  pounds  of 
air,  in  a  gasoline  engine,  and  the  engine  will 
supply  one  33,000-pound  horsepower  for  an 
hour.  The  gasoline  will  cost  about  2  cents, 
and  the  air  is  supplied  free.  If  it  was  the  air 
that  cost  two  cents  a  pound,  instead  of  the 


INTRODUCTION 


xix 


gasoline,  the  automobile  industry  would  un- 
doubtedly stop  where  it  began  some  fifteen 
years  ago.  It  is  human  nature,  however,  to 
grumble  over  this  two  cents. 

Yet  the  average  farmer  who  would  get 
excited  if  sound  young  chunks  and  drafters 
were  running  wild  across  his  pastures,  is  not 
inspired  by  any  similar  desire  of  possession 
and  mastery  by  the  sight  of  a  brook,  or  a 
rivulet  that  waters  his  meadows.  This  brook 
or  river  is  flowing  down  hill  to  the  sea.  Every 
4,000  gallons  that  falls  one  foot  in  one  minute; 
every  400  gallons  that  falls  10  feet  in  one 
minute;  or  every  40  gallons  that  falls  100 
feet  in  one  minute,  means  the  power  of  one 
horse  going  to  waste — not  the  $200  flesh- 
and-blood  kind  that  can  lift  only  23,000 
pounds  a  foot  a  minute — but  the  33,000 
foot-pound  kind.  Thousands  of  farms  have 
small  streams  in  their  very  dooryard,  capable 
of  developing  five,  ten,  twenty,  fifty  horse- 
power twenty-four  hours  a  day,  for  the  greater 
part  of  the  year.  Within  a  quarter  of  a  mile 
of  the  great  majority  of  farms  (outside  of  the 


xx  INTRODUCTION 

dry  lands  themselves)  there  are  such  streams. 
Only  a  small  fraction  of  one  per  cent  of  them 
have  been  put  to  work,  made  to  pay  their 
passage  from  the  hills  to  the  sea. 

The  United  States  government  geological 
survey  engineers  recently  made  an  estimate 
of  the  waterfalls  capable  of  developing  1,000 
horsepower  and  over,  that  are  running  to 
waste,  unused,  in  this  country.  They  esti- 
mated that  there  is  available,  every  second 
of  the  day  and  night,  some  30,000,000  horse- 
power, in  dry  weather — and  twice  this  during 
the  eight  wet  months  of  the  year.  The  water- 
fall capable  of  giving  up  1,000  horsepower  in 
energy  is  not  the  subject  of  these  chapters. 
It  is  the  small  streams — the  brooks,  the 
creeks,  the  rivulets — which  feed  the  1,000 
horsepower  torrents,  make  them  possible, 
that  are  of  interest  to  the  farmer.  These 
small  streams  thread  every  township,  every 
county,  seeking  the  easiest  way  to  the  main 
valleys  where  they  come  together  in  great 
rivers. 

What  profitable  crop  on  your  farm  removes 


INTRODUCTION 


xxi 


the  least  plant  food?  A  bee-farmer  enters 
his  honey  for  the  prize  in  this  contest.  Another 
farmer  maintains  that  his  ice-crop  is  the  win- 
ner. But  electricity  generated  from  falling 
water  of  a  brook  meandering  across  one's 
acres,  comes  nearer  to  the  correct  answer  of 
how  to  make  something  out  of  nothing.  It 
merely  utilizes  the  wasted  energy  of  water 
rolling  down  hill — the  weight  of  water,  the 
pulling  power  of  gravity.  Water  is  still 
water,  after  it  has  run  through  a  turbine  wheel 
to  turn  an  electric  generator.  It  is  still  wet; 
it  is  there  for  watering  the  stock;  and  a  few 
rods  further  down  stream,  where  it  drops 
five  or  ten  feet  again,  it  can  be  made  to  do 
the  same  work  over  again — and  over  and 
over  again  as  long  as  it  continues  to  fall,  on 
its  journey  to  the  sea.  The  city  of  Los  Angeles 
has  a  municipal  water  plant,  generating 
200,000  horsepower  of  electricity,  in  which 
the  water  is  used  three  times  in  its  fall  of 
6,000  feet;  and  in  the  end,  where  it  runs  out 
of  the  race  in  the  valley,  it  is  sold  for  irrigation. 
One  water-horsepower  will  furnish  light 


xxii  INTRODUCTION 

for  the  average  farm;  five  water-horsepower 
will  furnish  light  and  power,  and  do  the  iron- 
ing and  baking.  The  cost  of  installing  a  plant 
of  five  water-horsepower  should  not  exceed 
the  cost  of  one  sound  young  horse,  the  $200 
kind — under  conditions  which  are  to  be  found 
on  thousands  of  farms  and  farm  communities 
in  the  East,  the  Central  West,  and  the  Pacific 
States.  This  electrical  horsepower  will  work 
24  hours  a  day,  winter  and  summer,  and  the 
farmer  would  not  have  to  grow  oats  and  hay 
for  it  on  land  that  might  better  be  used  in 
growing  food  for  human  beings.  It  would 
not  become  "aged"  at  the  end  of  ten  or  fif- 
teen years,  and  the  expense  of  maintenance 
would  be  practically  nothing  after  the  first 
cost  of  installation.  It  would  require  only 
water  as  food — waste  water.  Two  hundred 
and  fifty  cubic  feet  of  water  a  minute,  falling 
ten  feet,  will  supply  the  average  farm  with 
all  the  conveniences  of  electricity.  This  is  a 
very  modest  creek — the  kind  of  brook  or 
creek  that  is  ignored  by  the  man  who  would 
think  time  well  spent  in  putting  in  a* week 


INTRODUCTION  xxiii 

capturing  a  wild  horse,  if  a  miracle  should 
send  such  a  beast  within  reach.  And  the 
task  of  harnessing  and  breaking  this  water- 
horsepower  is  much  more  simple  and  less 
dangerous  than  the  task  of  breaking  a  colt  to 
harness. 


PART  I 
WATER-POWER 


ELECTRICITY  FOR  THE  FARM 

CHAPTER  I 
A   WORKING   PLANT 

The  "agriculturist" — An  old  chair  factory — A  neigh- 
bor's home-coming — The  idle  wheel  hi  commission 
again — Light,  heat  and  power  for  nothing — Ad- 
vantages of  electricity. 

LET  us  take  an  actual  instance  of  one  man 
who  did  go  ahead  and  find  out  by  experience 
just  how  intricate  and  just  how  simple  a  thing 
electricity  from  farm  water-power  is.  This 
man's  name  was  Perkins,  or,  we  will  call  him 
that,  in  relating  this  story. 

Perkins  was  what  some  people  call,  not  a 
farmer,  but  an  "agriculturist,"-— that  is,  he 
was  a  back-to-the-land  man.  He  had  been 
born  and  raised  on  a  farm.  He  knew  that 
you  must  harness  a  horse  on  the  left  side, 
milk  a  cow  on  the  right,  that  wagon  nuts 
tighten  the  way  the  wheel  runs,  and  that  a 
fresh  egg  will  not  float. 

3 


ELECTRICITY  FOR  THE  FARM 

He  had  a  farm  that  would  grow  enough 
clover  to  fill  the  average  dairy  if  he  fed  it 
lime;  he  had  a  boy  coming  to  school  age;  and 
both  he  and  his  wife  wanted  to  get  back  to 
the  country.  They  had  their  little  savings, 
and  they  wanted,  first  of  all,  to  take  a  vaca- 
tion, getting  acquainted  with  their  farm. 
They  hadn't  taken  a  vacation  in  fifteen  years. 

He  moved  in,  late  in  the  summer,  and 
started  out  to  get  acquainted  with  his  neigh- 
bors, as  well  as  his  land.  This  was  in  the  New 
England  hills.  Water  courses  cut  through 
everywhere.  In  regard  to  its  bountiful  water 
supply,  the  neighborhood  had  much  in  com- 
mon with  all  the  states  east  of  the  Mississippi, 
along  the  Atlantic  seaboard,  in  the  lake  region 
of  the  central  west,  and  in  the  Pacific  States. 
With  this  difference;  the  water  courses  in  his 
neighborhood  had  once  been  of  economic  im- 
portance. 

A  mountain  river  flowed  down  his  valley. 
Up  and  down  the  valley  one  met  ramshackle 
mills,  fallen  into  decay.  Many  years  ago 
before  railroads  came,  before  it  was  easy  to 


A  WORKING  PLANT  5 

haul  coal  from  place  to  place  to  make  steam, 
these  little  mills  were  centers  of  thriving 
industries,  which  depended  on  the  power 
of  falling  water  to  make  turned  articles,  spin 
cotton,  and  so  forth.  Then  the  railroads 
came,  and  it  was  easy  to  haul  coal  to  make 
steam.  And  the  same  railroads  that  hauled 
the  coal  to  make  steam,  were  there  to  haul 
away  the  articles  manufactured  by  steam 
power.  So  in  time  the  little  manufacturing 
plants  on  the  river  back  in  the  hills  quit  busi- 
ness and  moved  to  railroad  stations.  Then 
New  England,  from  being  a  manufacturing 
community  made  up  of  many  small  isolated 
water  plants,  came  to  be  a  community  made 
up  of  huge  arteries  and  laterals  of  smoke 
stacks  that  fringed  the  railroads.  Where  the 
railroad  happened  to  follow  a  river  course- 
as  the  Connecticut  River — the  water-power 
plants  remained;  but  the  little  plants  back 
in  the  hills  were  wiped  off  the  map — because 
steam  power  with  railroads  at  the  front  door 
proved  cheaper  than  water-power  with  rail- 
roads ten  miles  away. 


6  ELECTRICITY  FOR  THE  FARM 

One  night  Perkins  came  in  late  from  a  long 
drive  with  his  next-door  neighbor.  He  had 
learned  the  first  rule  of  courtesy  in  the  coun- 
try, which  is  to  unhitch  his  own  side  of  the 
horse  and  help  back  the  buggy  into  the  shed. 
They  stumbled  around  in  the  barn  putting 
up  the  horse,  and  getting  down  hay  and  grain 
for  it,  by  the  light  of  an  oil  lantern,  which 
was  set  on  the  floor  in  a  place  convenient 
to  be  kicked  over.  He  went  inside  and  took 
supper  by  the  light  of  a  smoky  smelly  oil 
lamp,  that  filled  the  room  full  of  dark  corners ; 
and  when  supper  was  over,  the  farmwife 
groped  about  in  the  cellar  putting  things 
away  by  the  light  of  a  candle. 

The  next  day  his  neighbor  was  grinding 
cider  at  his  ramshackle  water  mill — one  of 
the  operations  for  which  a  week  must  be  set 
aside  every  fall.  Perkins  sat  on  a  log  and 
listened  to  the  crunch-crunch  of  the  apples 
in  the  chute,  and  the  drip  of  the  frothy  yellow 
liquid  that  fell  into  waiting  buckets. 

"How  much  power  have  you  got  here?" 
he  asked. 


A  WORKING  PLANT  7 

"Thirty  or  forty  horsepower,  I  guess." 

"What  do  you  do  with  it,  besides  grinding 
cider  to  pickle  your  neighbors'  digestion 
with?" 

"Nothing  much.  I've  got  a  planer  and  a 
moulding  machine  in  there,  to  work  up  jags 
of  lumber  occasionally.  That's  all.  This 
mill  was  a  chair-factory  in  my  grandfather's 
day,  back  in  1830." 

"Do  you  use  it  thirty  days  in  a  year? 

"No;  not  half  that." 

"What  are  you  going  to  do  with  it  this 
winter?" 

"Nothing;  I  keep  the  gate  open  and  the 
wheel  turning,  so  it  won't  freeze,  but  nothing 
else.  I  am  going  to  take  the  family  to  Texas 
to  visit  my  wife's  folks  for  three  months. 
We've  worked  hard  enough  to  take  a  vaca- 
tion." 

"Will  you  rent  me  the  mill  while  you  are 
gone?" 

"Go  ahead;  you  can  have  it  for  nothing,  if 
you  will  watch  the  ice." 

"All  right;  let  me  know  when  you  come 


8  ELECTRICITY  FOR  THE  FARM 

back  and  I'll  drive  to  town  and  bring  you 
home." 

Three  months  went  by,  and  one  day  in 
February  the  city  man,  in  response  to  a  letter, 
hitched  up  and  drove  to  town  to  bring  his 
neighbor  back  home.  It  was  four  o'clock 
in  the  afternoon  when  they  started  out,  and 
it  was  six — dark — when  they  turned  the  bend 
in  the  road  to  the  farm  house.  They  helped 
the  wife  and  children  out,  with  their  baggage, 
and  as  Perkins  opened  the  door  of  the  house, 
he  reached  up  on  the  wall  and  turned  some- 
thing that  clicked  sharply. 

Instantly  light  sprang  from  everywhere. 
In  the  barn-yard  a  street  lamp  with  an  18-inch 
reflector  illuminated  all  under  it  for  a  space 
of  100  feet  with  bright  white  rays  of  light. 
Another  street  lamp  hung  over  the  watering 
trough.  The  barn  doors  and  windows  burst 
forth  in  light.  There  was  not  a  dark  corner 
to  be  found  anywhere.  In  the  house  it  was 
the  same.  Perkins  led  the  amazed  procession 
from  room  to  room  of  the  house  they  had 


A  WORKING  PLANT  9 

shut  up  for  the  winter.  On  the  wall  in  the 
hall  outside  of  every  room  was  a  button  which 
he  pushed,  and  the  room  became  as  light  as 
day  before  they  entered.  The  cellar  door, 
in  opening,  automatically  lighted  a  lamp 
illuminating  that  cavern  as  it  had  never  been 
lighted  before  since  the  day  a  house  was  built 
over  it. 

Needless  to  say,  the  farmer  and  his  fam- 
ily were  reduced  to  a  state  of  speechless- 
ness. 

"How  the  deuce  did  you  do  it?"  finally 
articulated  the  farmer. 

"I  put  your  idle  water  wheel  to  work," 
said  Perkins;  and  then,  satisfied  with  this 
exhibition,  he  put  them  back  in  the  sleigh 
and  drove  to  his  home,  where  his  wife  had 
supper  waiting. 

While  the  men  were  putting  up  the  team  in 
the  electric  lighted  barn,  the  farmwife  went 
into  the  kitchen.  Her  hostess  was  cooking 
supper  on  an  electric  stove.  It  looked  like 
a  city  gas  range  and  it  cooked  all  their  meals, 
and  did  the  baking  besides.  A  hot- water  tank 


10          ELECTRICITY  FOR  THE  FARM 

stood  against  the  wall,  not  connected  to  any- 
thing hot,  apparently.  But  it  was  scalding 
hot,  by  virtue  of  a  little  electric  water  heater 
the  size  of  a  quart  tin  can,  connected  at  the 
bottom.  Twenty-four  hours  a  day  the  water 
wheel  pumped  electricity  into  that  "can," 
so  that  hot  water  was  to  be  had  at  any  hour 
simply  by  turning  a  faucet.  In  the  laundry 
there  was  an  electric  pump  that  kept  the  tank 
in  the  attic  filled  automatically.  When  the 
level  of  water  in  this  tank  fell  to  a  certain 
point,  a  float  operated  a  switch  that  started 
the  pump;  and  when  the  water  level  reached 
a  certain  height,  the  same  float  stopped  the 
pump.  A  small  motor,  the  size  of  a  medium 
Hubbard  squash  operated  a  washing  machine 
and  wringer  on  wash  days.  This  same  motor 
was  a  man-of-all-work  for  this  house,  for, 
when  called  on,  it  turned  the  separator, 
ground  and  polished  knives  and  silverware, 
spun  the  sewing  machine,  and  worked  the 
vacuum  cleaner. 

Over  the  dining  room  table  hung  the  same 
hanging  shade  of  old  days,  but  the  oil  lamp 


A  WORKING  PLANT  11 

itself  was  gone.  In  its  place  was  a  100-watt 
tungsten  lamp  whose  rays  made  the  white 
table  cloth  fairly  glisten.  The  wires  carrying 
electricity  to  this  lamp  were  threaded  through 
the  chains  reaching  to  the  ceiling,  and  one 
had  to  look  twice  to  see  where  the  current 
came  from.  In  the  sitting  room,  a  cluster  of 
electric  bulbs  glowed  from  a  fancy  wicker  work 
basket  that  hung  from  the  ceiling.  The  house- 
wife had  made  use  of  what  she  had  through- 
out the  house.  Old-fashioned  candle-shades 
sat  like  cocked  hats  astride  electric  bulbs. 
There  is  little  heat  to  an  electric  bulb  for  the 
reason  that  the  white-hot  wire  that  gives 
the  light  is  made  to  burn  in  high  vacuum, 
which  transmits  heat  very  slowly.  The  house- 
wife had  taken  advantage  of  this  fact  and 
from  every  corner  gleamed  lights  dressed  in 
fancy  designs  of  tissue  paper  and  silk. 

"Now  we  will  talk  business,"  said  Perkins 
when  supper  was  over  and  they  had  lighted 
their  pipes. 

The  returned  native  looked  dubious.  His 
New  England  training  had  warned  him  long 


12          ELECTRICITY  FOR  THE  FARM 

ago  that  one  cannot  expect  to  get  something 
for  nothing,  and  he  felt  sure  there  was  a  joker 
in  this  affair. 

"How  much  do  I  owe  you?"  he  asked. 

"Nothing,"  said  Perkins.  "You  furnish 
the  water-power  with  your  idle  wheel,  and  I 
furnish  the  electric  installation.  This  is  only 
a  small  plant  I  have  put  in,  but  it  gives  us 
enough  electricity  to  go  around,  with  a  margin 
for  emergencies.  I  have  taken  the  liberty  of 
wiring  your  house  and  your  horse-barn  and 
cow-barn  and  your  barn-yard.  Altogether,  I 
suppose  you  have  30  lights  about  the  place, 
and  during  these  long  winter  days  you  will 
keep  most  of  them  going  from  3  to  5  hours  a 
night  and  2  or  3  hours  in  the  early  morning. 
If  you  were  in  town,  those  lights  would  cost 
you  about  12  cents  an  hour,  at  the  commercial 
rate  of  electricity.  Say  60  cents  a  day — 
eighteen  dollars  a  month.  That  isn't  a  very 
big  electric  light  bill  for  some  people  I  know 
in  town — and  they  consider  themselves  lucky 
to  have  the  privilege  of  buying  electricity  at 
that  rate.  Your  wheel  is  running  all  winter  to 


A  WORKING  PLANT  IS 

prevent  ice  from  forming  and  smashing  it. 
It  might  just  as  well  be  spinning  the  dynamo. 

"If  you  think  it  worth  while,"  continued 
Perkins,— "this  $18  worth  of  light  you  have 
on  tap  night  and  morning,  or  any  hour  of  the 
day, — we  will  say  the  account  is  settled. 
That  is,  of  course,  if  you  will  give  me  the  use 
of  half  the  electricity  that  your  idle  wheel  is 
grinding  out  with  my  second-hand  dynamo. 
We  have  about  eight  electrical  horsepower  on 
our  wires,  without  overloading  the  machine. 
Next  spring  I  am  going  to  stock  up  this  place; 
and  I  think  about  the  first  thing  I  do,  when 
my  dairy  is  running,  will  be  to  put  in  a  milk- 
ing machine  and  let  electricity  do  the  milking 
for  me.  It  will  also  fill  my  silo,  grind  my 
mowing-machine  knives,  saw  my  wood,  and 
keep  water  running  in  my  barn.  You  will 
probably  want  to  do  the  same. 

"But  what  it  does  for  us  men  in  the  barn  and 
barn-yard,  isn't  to  be  compared  to  what  it  does 
for  the  women  in  the  house.  When  my  wife 
wants  a  hot  oven  she  presses  a  button.  When 
she  wants  to  put  the  'fire'  out,  she  presses 


14          ELECTRICITY  FOR  THE  FARM 

another.  That's  all  there  is  to  it.  No  heat, 
no  smoke,  no  ashes.  The  same  with  ironing — 
and  washing.  No  oil  lamps  to  fill,  no  wicks  to 
trim,  no  chimneys  to  wash,  no  kerosene  to 
kick  over  and  start  a  fire." 

"You  say  the  current  you  have  put  in  my 
house  would  cost  me  about  $18  a  month,  in 
town." 

"Yes,  about  that.  Making  electricity  from 
coal  costs  money." 

"What  does  it  cost  here?" 

"Practically  nothing.  Your  river,  that  has 
been  running  to  waste  ever  since  your  grand- 
father gave  up  making  chairs,  does  the  work. 
There  is  nothing  about  a  dynamo  to  wear  out, 
except  the  bearings,  and  these  can  be  replaced 
once  every  five  or  ten  years  for  a  trifle.  The 
machine  needs  to  be  oiled  and  cared  for — fill 
the  oil  cups  about  once  in  three  days.  Your 
water  wheel  needs  the  same  attention.  That's 
all  there  is  to  it.  You  can  figure  the  cost  of 
your  current  yourself — just  about  the  cost 
of  the  lubricating  oil  you  use — and  the  cost 
of  the  time  you  give  it — about  the  same  time 


A  WORKING  PLANT  15 

you  give  to  any  piece  of  good  machinery, 
from  a  sulky  plow  to  a  cream  separator." 

This  is  a  true  story.  This  electric  plant, 
where  Perkins  furnishes  the  electric  end,  and 
his  neighbor  the  water-power,  has  been  running 
now  for  two  years,  grinding  out  electricity  for 
the  two  places  twenty-four  hours  a  day. 
Perkins  was  not  an  electrical  engineer.  He 
was  just  a  plain  intelligent  American  citizen 
who  found  sufficient  knowledge  in  books  to 
enable  him  to  install  and  operate  this  plant. 
Frequently  he  is  away  for  long  periods,  but 
his  neighbor  (who  has  lost  his  original  terror 
of  electricity)  takes  care  of  the  plant.  In  fact, 
this  farmer  has  given  a  lot  of  study  to  the 
thing,  through  curiosity,  until  he  knows 
fully  as  much  about  it  now  as  his  city 
neighbor. 

He  had  the  usual  idea,  at  the  start,  that  a 
current  strong  enough  to  light  a  100  candle- 
power  lamp  would  kick  like  a  mule  if  a  man 
happened  to  get  behind  it.  He  watched  the 
city  man  handle  bare  wires  and  finally  he 
plucked  up  courage  to  do  it  himself. 


16          ELECTRICITY  FOR  THE  FARM 

It  was  a  110- volt  current,  the  pressure 
used  in  our  cities  for  domestic  lighting.  The 
funny  part  about  it  was,  the  farmer  could 
not  feel  it  at  all  at  first.  His  fingers  were 
calloused  and  no  current  could  pass  through 
them.  Finally  he  sandpapered  his  fingers 
and  tried  it  again.  Then  he  was  able  to  get 
the  "tickle"  of  110  volts.  It  wasn't  so  deadly 
after  all — about  the  strength  of  a  weak  medi- 
cal battery,  with  which  every  one  is  familiar. 
A  current  of  110  volts  cannot  do  any  harm  to 
the  human  body  unless  contact  is  made  over 
a  very  large  surface,  which  is  impossible 
unless  a  man  goes  to  a  lot  of  trouble  to  make 
such  a  contact.  A  current  of  220  volts  pres- 
sure— the  pressure  used  in  cities  for  motors- 
has  a  little  more  "kick"  to  it,  but  still  is  not 
uncomfortable.  When  the  pressure  rises  to 
500  volts  (the  pressure  used  in  trolley  wires 
for  street  cars),  it  begins  to  be  dangerous. 
But  there  is  no  reason  why  a  farm  plant  should 
be  over  110  volts,  under  usual  conditions; 
engineers  have  decided  on  this  pressure  as 
the  best  adapted  to  domestic  use,  and  manu- 


A  WORKING  PLANT  17 

facturers  who  turn  out  the  numerous  electri- 
cal devices,  such  as  irons,  toasters,  massage 
machines,  etc.,  fit  their  standard  instruments 
to  this  voltage. 

As  to  the  cost  of  this  co-operative  plant — 
it  was  in  the  neighborhood  of  $200.  As  we 
have  said,  it  provided  eight  electrical  horse- 
power on  tap  at  any  hour  of  the  day  or  night — 
enough  for  the  two  farms,  and  a  surplus  for 
neighbors,  if  they  wished  to  string  lines  and 
make  use  of  it. 

The  dynamo,  a  direct-current  machine, 
110  volts  pressure,  and  what  is  known  in  the 
trade  as  "compound,"-— that  is,  a  machine 
that  maintains  a  constant  pressure  auto- 
matically and  does  not  require  an  attendant — 
was  picked  up  second-hand,  through  a  news- 
paper "ad"  and  cost  $90.  The  switchboard, 
a  make-shift  affair,  not  very  handsome,  but 
just  as  serviceable  as  if  it  were  made  of  mar- 
ble, cost  less  than  $25  all  told.  The  trans- 
mission wire  cost  $19  a  hundred  pounds;  it 
is  of  copper,  and  covered  with  weatherproofed 
tape.  Perkins  bought  a  50-cent  book  on 


18          ELECTRICITY  FOR  THE  FARM 

house-wiring,  and  did  the  wiring  himself, 
the  way  the  book  told  him  to,  a  simple  opera- 
tion. For  fixtures,  as  we  have  said,  his  wife 
devised  fancy  shades  out  of  Mexican  baskets, 
tissue  paper,  and  silk,  in  which  are  hidden 
electric  globes  that  glow  like  fire-flies  at  the 
pressing  of  a  button.  The  lamps  themselves 
are  mostly  old-style  carbon  lamps,  which  can 
be  bought  at  16  cents  each  retail.  In  his 
living  room  and  dining  room  he  used  the  new- 
style  tungsten  lamps  instead  of  old-style 
carbon.  These  cost  30  cents  each.  Incandes- 
cent lamps  are  rated  for  1,000  hours  useful 
life.  The  advantage  of  tungsten  lights  is 
that  they  give  three  times  as  much  light  for 
the  same  expenditure  of  current  as  carbon 
lights.  This  is  a  big  advantage  in  the  city, 
where  current  is  costly;  but  it  is  not  so  much 
of  an  advantage  in  the  country  where  a  farmer 
has  plenty  of  water-power — because  his  cur- 
rent costs  him  practically  nothing,  and  he 
can  afford  to  be  wasteful  of  it  to  save  money  in 
lamps.  Another  advantage  he  has  over  his 
city  cousin:  In  town,  an  incandescent  lamp  is 


A  WORKING  PLANT  19 

thrown  away  after  it  has  been  used  1,000  hours 
because  after  that  it  gives  only  80%  of  the 
light  it  did  when  new — quite  an  item  when 
one  is  paying  for  current.  The  experience 
of  Perkins  and  his  neighbor  in  their  coopera- 
tive plant  has  been  that  they  have  excess 
light  anyway,  and  if  a  few  bulbs  fall  off  a 
fifth  in  efficiency,  it  is  not  noticeable.  As  a 
matter  of  fact  most  of  their  bulbs  have  been 
in  use  without  replacing  for  the  two  years  the 
plant  has  been  in  operation.  The  lamps  are 
on  the  wall  or  the  ceiling,  out  of  the  way, 
not  liable  to  be  broken;  so  the  actual  expense 
in  replacing  lamps  is  less  than  for  lamp  chim- 
neys in  the  old  days. 

Insurance  companies  recognize  that  a  large 
percentage  of  farm  fires  comes  from  the  use 
of  kerosene;  for  this  reason,  they  are  willing 
to  make  special  rates  for  farm  homes  lighted 
by  electricity.  They  prescribe  certain  rules 
for  wiring  a  house,  and  they  insist  that  their 
agent  inspect  and  pass  such  wiring  before 
current  is  turned  on.  Once  the  wiring  is 
passed,  the  advantage  is  all  in  favor  of  the 


20          ELECTRICITY  FOR  THE  FARM 

farmer  with  electricity  over  the  farmer  with 
kerosene.  The  National  Board  of  Fire  Under- 
writers is  sufficiently  logical  in  its  demands, 
and  powerful  enough,  so  that  manufacturers 
who  turn  out  the  necessary  fittings  find  no 
sale  for  devices  that  do  not  conform  to  insur- 
ance standards.  Therefore  it  is  difficult  to 
go  wrong  in  wiring  a  house. 

Finally,  as  to  the  added  value  a  water- 
power  electric  plant  adds  to  the  selling  price 
of  a  farm.  Let  the  farmer  answer  this  ques- 
tion for  himself.  If  he  can  advertise  his  farm 
for  sale,  with  a  paragraph  running:  "Hydro- 
electric plant  on  the  premises,  furnishing 
electricity  for  light,  heat,  and  power" 
what  do  you  suppose  a  wide-awake  purchaser 
would  be  willing  to  pay  for  that?  Perkins 
and  his  neighbor  believe  that  $1,000  is  a  very 
modest  estimate  added  by  their  electric  plant 
to  both  places.  And  they  talk  of  doing  still 
more.  They  use  only  a  quarter  of  the  power 
of  the  water  that  is  running  to  waste  through 
the  wheel.  They  are  figuring  on  installing 
a  larger  dynamo,  of  say  30  electrical  horse- 


A  WORKING  PLANT  21 

power,  which  will  provide  clean,  dry,  safe 
heat  for  their  houses  even  on  the  coldest 
days  in  winter.  When  they  have  done  this, 
they  will  consider  that  they  are  really  putting 
their  small  river  to  work. 


CHAPTER  II 

A   LITTLE   PROSPECTING 

Small  amount  of  water  required  for  an  electric  plant — 
Exploring,  on  a  dull  day — A  rough  and  ready 
weir — What  a  little  water  will  do — The  water 
wheel  and  the  dynamo — Electricity  consumed 
the  instant  it  is  produced — The  price  of  the  aver- 
age small  plant,  not  counting  labor. 

THE  average  farmer  makes  the  mistake 
of  considering  that  one  must  have  a  river 
of  some  size  to  develop  power  of  any  practical 
use.  On  your  next  free  day  do  a  little  pros- 
pecting. We  have  already  said  that  250 
cubic  feet  of  water  falling  10  feet  a  minute 
will  provide  light,  heat  and  small  motor 
power  for  the  average  farm.  A  single  water 
horsepower  will  generate  enough  electricity 
to  provide  light  for  the  house  and  barn.  But 
let  us  take  five  horsepower  as  a  desirable 
minimum  in  this  instance. 

In  your  neighborhood  there  is  a  creek  three 


sc 
c 
•c 


A  LITTLE  PROSPECTING  23 

or  four  feet  wide,  toiling  along  day  by  day, 
at  its  task  of  watering  your  fields.  Find  a 
wide  board  a  little  longer  than  the  width  of 
this  creek  you  have  scorned.  Set  it  upright 
across  the  stream  between  the  banks,  so  that 
no  water  flows  around  the  ends  or  under  it. 
It  should  be  high  enough  to  set  the  water 
back  to  a  dead  level  for  a  few  feet  upstream, 
before  it  overflows.  Cut  a  gate  in  this  board, 
say  three  feet  wide  and  ten  inches  deep,  or 
according  to  the  size  of  a  stream.  Cut  this 
gate  from  the  top,  so  that  all  the  water  of  the 
stream  will  flow  through  the  opening,  and 
still  maintain  a  level  for  several  feet  back 
of  the  board. 

This  is  what  engineers  call  a  weir,  a  handy 
contrivance  for  measuring  the  flow  of  small 
streams.  Experts  have  figured  out  an  elabo- 
rate system  of  tables  as  to  weirs.  All  we 
need  to  do  now,  in  this  rough  survey,  is  to 
figure  out  the  number  of  square  inches  of 
water  flowing  through  this  opening  and  falling 
on  the  other  side.  With  a  rule,  measure  the 
depth  of  the  overflowing  water,  from  the  bot- 


24          ELECTRICITY  FOR  THE  FARM 

torn  of  the  opening  to  the  top  of  the  dead 
level  of  the  water  behind  the  board.  Mul- 
tiply this  depth  by  the  width  of  the  opening, 
which  will  give  the  square  inches  of  water 
escaping.  For  every  square  inch  of  this  water 
escaping,  engineers  tell  us  that  stream  is 
capable  of  delivering,  roughly,  one  cubic  foot 
of  water  a  minute. 

Thus,  if  the  water  is  8  inches  deep  in  an 
opening  32  inches  wide,  then  the  number  of 
cubic  feet  this  stream  is  delivering  each  min- 
ute is  8  times  32,  or  256  cubic  feet  a  minute. 
So,  a  stream  32  inches  wide,  with  a  uniform 
depth  of  8  inches  running  through  our  weir 
is  capable  of  supplying  the  demands  of  the 
average  farm  in  terms  of  electricity.  Pro- 
viding, of  course,  that  the  lay  of  the  land  is 
such  that  this  water  can  be  made  to  fall  10 
feet  into  a  water  wheel. 

Go  upstream  and  make  a  rough  survey  of 
the  fall.  In  the  majority  of  instances  (unless 
this  is  some  sluggish  stream  in  a  flat  prairie) 
it  will  be  found  feasible  to  divert  the  stream 
from  its  main  channel  by  means  of  a  race — an 


A  LITTLE  PROSPECTING  25 

artificial  channel — and  to  convey  it  to  a  not 
far-distant  spot  where  the  necessary  fall  can 
be  had  at  an  angle  of  about  30  degrees  from 
horizontal. 

If  you  find  there  is  twice  as  much  water  as 
you  need  for  the  amount  of  power  you  require, 
a  five-foot  fall  will  give  the  same  result.  Or,  if 
there  is  only  one-half  as  much  water  as  the  250 
cubic  feet  specified,  you  can  still  obtain  your 
theoretical  five  horsepower  if  the  means  are  at 
hand  for  providing  a  fall  of  twenty  feet  in- 
stead of  ten.  Do  not  make  the  very  common 
mistake  of  figuring  that  a  stream  is  delivering 
a  cubic  foot  a  minute  to  each  square  inch  of 
weir  opening,  simply  because  it  fills  a  certain 
opening.  It  is  the  excess  water,  falling  over 
the  opening,  after  the  stream  has  set  back  to  a 
permanent  dead  level,  that  is  to  be  measured. 

This  farmer  who  spends  an  idle  day  meas- 
uring the  flow  of  his  brook  with  a  notched 
board,  may  say  here:  "This  is  all  very  well. 
This  is  the  spring  of  the  year,  when  my  brook 
is  flowing  at  high-water  mark.  What  am  I 
going  to  do  in  the  dry  months  of  summer,  when 


26  ELECTRICITY  FOR  THE  FARM 

there  are  not  250  cubic  feet  of  water  escaping 
every  minute?" 

There  are  several  answers  to  this  question, 
which  will  be  taken  up  in  detail  in  subsequent 
chapters.  Here,  let  us  say,  even  if  this  brook 
does  flow  in  sufficient  volume  only  8  months 
in  a  year — the  dark  months,  by  the  way, — is 
not  electricity  and  the  many  benefits  it  pro- 
vides worth  having  eight  months  in  the  year? 
My  garden  provides  fresh  vegetables  four 
months  a  year.  Because  it  withers  and  dies 
and  lies  covered  with  snow  during  the  winter, 
is  that  any  reason  why  I  should  not  plow  and 
manure  and  plant  my  garden  when  spring 
comes  again? 

A  water  wheel,  the  modern  turbine,  is  a 
circular  fan  with  curved  iron  blades,  revolving 
in  an  iron  case.  Water,  forced  through  the 
blades  of  this  fan  by  its  own  weight,  causes  the 
wheel  to  revolve  on  its  axis;  and  the  fan,  in 
turn  causes  a  shaft  fitted  with  pulleys  to  re- 
volve. 

The  water,  by  giving  the  iron-bladed  fan  a 
turning  movement  as  it  rushes  through,  im- 


A  LITTLE  PROSPECTING  27 

parts  to  it  mechanical  power.  The  shaft 
set  in  motion  by  means  of  this  mechanical 
power  is,  in  turn,  belted  to  the  pulley  of  a 
dynamo.  This  dynamo  consists,  first,  of  a 
shaft  on  which  is  placed  a  spool,  wound  in  a 
curious  way,  with  many  turns  of  insulated 
copper  wire.  This  spool  revolves  freely  in  an 
air  space  surrounded  by  electric  magnets. 
The  spool  does  not  touch  these  magnets.  It 
is  so  nicely  balanced  that  the  weight  of  a 
finger  will  turn  it.  Yet,  when  it  is  revolved 
by  water-power  at  a  predetermined  speed — 
say  1,500  revolutions  a  minute — it  generates 
electricity,  transforms  the  mechanical  power 
of  the  water  wheel  into  another  form  of  en- 
ergy— a  form  of  energy  which  can  be  carried 
for  long  distances  on  copper  wires,  which  can, 
by  touching  a  button,  be  itself  converted  into 
light,  or  heat,  or  back  into  mechanical  energy 
again. 

If  two  wires  be  led  from  opposite  sides  of 
this  revolving  spool,  and  an  electric  lamp  be 
connected  from  one  to  the  other  wire,  the 
lamp  will  be  lighted — will  grow  white  hot, — 


28          ELECTRICITY  FOR  THE  FARM 

hence  incandescent  light.  The  instant  this 
lamp  is  turned  on,  the  revolving  spool  feels 
a  stress,  the  magnets  by  which  it  is  surrounded 
begin  to  pull  back  on  it.  The  power  of  the 
water  wheel,  however,  overcomes  this  pull. 
If  one  hundred  lights  be  turned  on,  the  back- 
ward pull  of  the  magnets  surrounding  the 
spool  will  be  one  hundred  times  as  strong  as 
for  one  light.  For  every  ounce  of  electrical 
energy  used  in  light  or  heat  or  power,  the 
dynamo  will  require  a  like  ounce  of  me- 
chanical power  from  the  water  wheel  which 
drives  it. 

The  story  is  told  of  a  canny  Scotch  engineer, 
who,  in  the  first  days  of  dynamos,  not  so  very 
long  ago,  scoffed  at  the  suggestion  that  such 
a  spool,  spinning  in  free  air,  in  well  lubricated 
bearings,  could  bring  his  big  Corliss  steam 
engine  to  a  stop.  Yet  he  saw  it  done  simply 
by  belting  this  "spool,"  a  dynamo,  to  his 
engine  and  asking  the  dynamo  for  more  power 
in  terms  of  light  than  his  steam  could  deliver 
in  terms  of  mechanical  power  to  overcome  the 
pull  of  the  magnets. 


A  LITTLE  PROSPECTING  29 

Electricity  must  be  consumed  the  instant 
it  is  generated  (except  in  rare  instances  where 
small  amounts  are  accumulated  in  storage 
batteries  by  a  chemical  process) .  The  pressure 
of  a  button,  or  the  throw  of  a  switch  causes  the 
dynamo  instantly  to  respond  with  just  enough 
energy  to  do  the  work  asked  of  it,  always  in 
proportion  to  the  amount  required.  Having 
this  in  mind,  it  is  rather  curious  to  think  of 
electricity  as  being  an  article  of  export,  an 
item  in  international  trade.  Yet  in  1913 
hydro-electric  companies  in  Canada  "ex- 
ported" by  means  of  wires,  to  this  country 
over  772,000,000  kilowatt-hours  (over  one 
billion  horsepower  hours)  of  electricity 
for  use  in  factories  near  the  boundary 
line. 

This  250  cubic  feet  of  water  per  minute  then, 
which  the  farmer  has  measured  by  means  of 
his  notched  board,  will  transform  by  means  of 
its  falling  weight  mechanical  power  into  a 
like  amount  of  electrical  power — less  friction 
losses,  which  may  amount  to  as  much  as  60% 
in  very  small  machines,  and  15%  in  larger 


SO          ELECTRICITY  FOR  THE  FARM 

plants.  That  is,  the  brook  which  has  been 
draining  your  pastures  for  uncounted  ages 
contains  the  potential  power  of  3  and  4  young 
horses — with  this  difference:  that  it  works  24 
hours  a  day,  runs  on  forever,  and  requires  no 
oats  or  hay.  And  the  cost  of  such  an  electric 
plant,  which  is  ample  for  the  needs  of  the 
average  farm,  is  in  most  cases  less  than  the 
price  of  a  good  farm  horse — the  $200  kind— 
not  counting  labor  of  installation. 

It  is  the  purpose  of  these  chapters  to  awaken 
the  farmer  to  the  possibilities  of  such  small 
water-power  as  he  or  his  community  may 
possess;  to  show  that  the  generating  of  elec- 
tricity is  a  very  simple  operation,  and  that 
the  maintenance  and  care  of  such  a  plant  is 
within  the  mechanical  ability  of  any  American 
farmer  or  farm  boy;  and  to  show  that  elec- 
tricity itself  is  far  from  being  the  dangerous 
death-dealing  "fluid"  of  popular  imagination. 
Electricity  must  be  studied;  and  then  it 
becomes  an  obedient,  tireless  servant.  During 
the  past  decade  or  two,  mathematical  wizards 
have  studied  electricity,  explored  its  atoms, 


A  LITTLE  PROSPECTING  31 

reduced  it  to  simple  arithmetic — and  although 
they  cannot  yet  tell  us  why  it  is  generated, 
they  tell  us  how.  It  is  with  this  simple  arith- 
metic, and  the  necessary  manual  operations 
that  we  have  to  do  here. 


CHAPTER  III 

HOW   TO    MEASURE    WATER-POWER 

What  is  a  horsepower? — How  the  Carthaginians  manu- 
factured horsepower — All  that  goes  up  must  come 
down — How  the  sun  lifts  water  up  for  us  to  use — 
Water  the  ideal  power  for  generating  electricity — 
The  weir — Table  for  estimating  flow  of  streams, 
with  a  weir — Another  method  of  measuring — 
Figuring  water  horsepower — The  size  of  the  wheel 
— What  head  is  required — Quantity  of  water 
necessary. 

IF  a  man  were  off  in  the  woods  and  needed  a 
horsepower  of  energy  to  work  for  him,  he 
could  generate  it  by  lifting  550  pounds  of 
stone  or  wood,  or  whatnot,  one  foot  off  the 
ground,  and  letting  it  fall  back  in  the  space  of 
one  second.  As  a  man  possesses  capacity  for 
work  equal  to  one-fifth  horsepower,  it  would 
take  him  five  seconds  to  do  the  work  of  lifting 
the  weight  up  that  the  weight  itself  accom- 
plished in  falling  down.  All  that  goes  up 
must  come  down;  and  by  a  nice  balance  of 

32 


HOW  TO  MEASUKE  WATER-POWER      33 

physical  laws,  a  falling  body  hits  the  ground 
with  precisely  the  same  force  as  is  re- 
quired to  lift  it  to  the  height  from  which  it 
falls. 

The  Carthaginians,  and  other  ancients  (who 
were  deep  in  the  woods  as  regards  mechanical 
knowledge)  had  their  slaves  carry  huge  stones 
to  the  top  of  the  city  wall;  and  the  stones  were 
placed  in  convenient  positions  to  be  tipped 
over  on  the  heads  of  any  besieging  army  that 
happened  along.  Thus  by  concentrating  the 
energy  of  many  slaves  in  one  batch  of  stones, 
the  warriors  of  that  day  were  enabled  to  de- 
liver "horsepower"  in  one  mass  where  it 
would  do  the  most  good.  The  farmer  who 
makes  use  of  the  energy  of  falling  water  to 
generate  electricity  for  light,  heat,  and  power 
does  the  same  thing — he  makes  use  of  the 
capacity  for  work  stored  in  water  in  being 
lifted  to  a  certain  height.  As  in  the  case  of 
the  gasoline  engine,  which  burns  14  pounds  of 
air  for  every  pound  of  gasoline,  the  engineer 
of  the  water-power  plant  does  not  have  to 
concern  himself  with  the  question  of  how  this 


34  ELECTRICITY  FOR  THE  FARM 

natural  source  of  energy  happened  to  be  in  a 
handy  place  for  him  to  make  use  of  it. 

The  sun,  shining  on  the  ocean,  and  turning 
water  into  vapor  by  its  heat  has  already  lifted 
it  up  for  him.  This  vapor  floating  in  the  air 
and  blown  about  by  winds,  becomes  chilled 
from  one  cause  or  another,  gives  up  its  heat, 
turns  back  into  water,  and  falls  as  rain.  This 
rain,  falling  on  land  five,  ten,  a  hundred,  a 
thousand,  or  ten  thousand  feet  above  the  sea 
level,  begins  to  run  back  to  the  sea,  picking  out 
the  easiest  road  and  cutting  a  channel  that  we 
call  a  brook,  a  stream,  or  a  river.  Our  farm 
lands  are  covered  to  an  average  depth  of 
about  three  feet  a  year  with  water,  every 
gallon  of  which  has  stored  in  it  the  energy 
expended  by  the  heat  of  the  sun  in  lifting  it 
to  the  height  where  it  is  found. 

The  farmer,  prospecting  on  his  land  for 
water-power,  locates  a  spot  on  a  stream  which 
he  calls  Supply;  and  another  spot  a  few  feet 
down  hill  near  the  same  stream,  which  he  calls 
Power.  Every  gallon  of  water  that  falls 
between  these  two  points,  and  is  made  to 


HOW  TO  MEASURE  WATER-POWER      35 

escape  through  the  revolving  blades  of  a 
water  wheel  is  capable  of  work  in  terms  of 
foot-pounds — an  amount  of  work  that  is 
directly  proportional  to  the  quantity  of  water, 
and  to  the  distance  in  feet  which  it  falls  to 
reach  the  wheel — pounds  smdfeet. 

The  Efficient  Water  Wheel 

And  it  is  a  very  efficient  form  of  work,  too. 
In  fact  it  is  one  of  the  most  efficient  forms  of 
mechanical  energy  known — and  one  of  the 
easiest  controlled.  A  modern  water  wheel 
uses  85  per  cent  of  the  total  capacity  for  work 
imparted  to  falling  water  by  gravity,  and 
delivers  it  as  rotary  motion.  Compare  this 
water  wheel  efficiency  with  other  forms  of 
mechanical  power  in  common  use:  Whereas  a 
water  wheel  uses  85  per  cent  of  the  energy 
of  its  water  supply,  and  wastes  only  15  per 
cent,  a  gasoline  engine  reverses  the  table,  and 
delivers  only  15  per  cent  of  the  energy  in 
gasoline  and  wastes  85  per  cent — and  it  is 
rather  a  high-class  gasoline  engine  that  can 
deliver  even  15  per  cent;  a  steam  engine,  on 


36          ELECTRICITY  FOR  THE  FARM 

the  other  hand,  uses  about  17  per  cent  of 
the  energy  in  the  coal  under  its  boilers  and 
passes  the  rest  up  the  chimney  as  waste  heat 
and  smoke. 

There  is  still  another  advantage  possessed 
by  water-power  over  its  two  rivals,  steam  and 
gas:  It  gives  the  most  even  flow  of  power. 
A  gas  engine  "kicks"  a  wheel  round  in  a 
circle,  by  means  of  successive  explosions  in 
its  cylinders.  A  reciprocating  steam  engine 
"kicks"  a  wheel  round  in  a  circle  by  means  of 
steam  expanding  first  in  one  direction,  then  in 
another.  A  water  wheel,  on  the  other  hand, 
is  made  to  revolve  by  means  of  the  pressure  of 
water — by  the  constant  force  of  gravity, 
itself — weight.  Weight  is  something  that 
does  not  vary  from  minute  to  minute,  or  from 
one  fraction  of  a  second  to  another.  It  is 
always  the  same.  A  square  inch  of  water 
pressing  on  the  blades  of  a  water  wheel 
weights  ten,  twenty,  a  hundred  pounds, 
according  to  the  height  of  the  pipe  conveying 
that  water  from  the  source  of  supply,  to  the 
wheel.  So  long  as  this  column  of  water  is 


HOW  TO  MEASURE  WATER-POWER      37 

maintained  at  a  fixed  height,  the  power  it 
delivers  to  the  wheel  does  not  vary  by  so 
much  as  the  weight  of  a  feather. 

This  property  of  falling  water  makes  it  the 
ideal  power  for  generating  electricity.  Elec- 
tricity generated  from  mechanical  power  de- 
pends on  constant  speed  for  steady  pressure — 
since  the  electric  current,  when  analyzed,  is 
merely  a  succession  of  pulsations  through  a 
wire,  like  waves  beating  against  a  sea  wall. 
Water-power  delivers  these  waves  at  a  con- 
stant speed,  so  that  electric  lights  made  from 
water-power  do  not  flicker  and  jump  like  the 
flame  of  a  lantern  in  a  gusty  wind.  On  the 
other  hand,  to  accomplish  the  same  thing  with 
steam  or  gasoline  requires  an  especially  con- 
structed engine. 

The  Simple  Weir 

Since  a  steady  flow  of  water,  and  a  constant 
head,  bring  about  this  ideal  condition  in  the 
water  wheel,  the  first  problem  that  faces  the 
farmer  prospector  is  to  determine  the  amount 
of  water  which  his  stream  is  capable  of  de- 


38  ELECTRICITY  FOR  THE  FARM 

livering.  This  is  always  measured,  for  con- 
venience, in  cubic  feet  per  minute.  (A  cubic 
foot  of  water  weighs  62.5  pounds,  and  con- 
tains 7%  gallons.)  This  measurement  is  ob- 
tained in  several  ways,  among  which  prob- 
ably the  use  of  a  weir  is  the  simplest  and  most 
accurate,  for  small  streams. 

A  weir  is,  in  effect,  merely  a  temporary  dam 
set  across  the  stream  in  such  a  manner  as  to 
form  a  small  pond;  and  to  enable  one  to 
measure  the  water  escaping  from  this  pond. 

It  may  be  likened 
to  the  overflow 
pipe  of  a  horse 
trough  which  is 
being  fed  from  a 
spring.  Tomeas- 

Detail  of  home-made  weir  ure     jj^     fJQW    Qf 

water  from  such  a  spring,  all  that  is  necessary 
is  to  measure  the  water  escaping  through  the 
overflow  when  the  water  in  the  trough  has 
attained  a  permanent  level. 

The  diagrams  show  the  cross-section  and 
detail  of  a  typical  weir,  which  can  be  put 


HOW  TO  MEASURE  WATER-POWER      39 


together  in  a  few  minutes  with  the  aid  of  a 
saw  and  hammer.  The  cross-section  shows 
that  the  lower  edge  of  the  slot  through  which 
the  water  of  the  temporary  pond  is  made  to 
escape,  is  cut  on  a  bevel,  with  its  sharp  edge 
upstream.  The  wing  on  each  side  of  the 
opening  is  for  the  purpose  of  preventing  the 
stream  from  narrowing  as  it  flows  through  the 
opening,  and  thus  upsetting  the  calculations. 
This  weir  should 


be  set  directly 
across  the  flow 
of  the  stream, 
perfectly  level, 
and  upright.  It 
should  be  so  im- 
bedded in  the  banks,  and  in  the  bottom 
of  the  stream,  that  no  water  can  escape, 
except  through  the  opening  cut  for  that 
purpose.  It  will  require  a  little  experi- 
menting with  a  rough  model  to  determine 
just  how  wide  and  how  deep  this  opening 
should  be.  It  should  be  large  enough  to 
prevent  water  flowing  over  the  top  of  the 


Cross-section  of  weir 


40  ELECTRICITY  FOR  THE  FARM 

board;  and  it  should  be  small  enough  to  cause 
a  still-water  pond  to  form  for  several  feet 
behind  the  weir.  Keep  in  mind  the  idea  of 
the  overflowing  water  trough  when  building 
your  weir.  The  stream,  running  down  from  a 
higher  level  behind,  should  be  emptying  into 
a  still- water  pond,  which  in  turn  should  be 
emptying  itself  through  the  aperture  in  the 
board  at  the  same  rate  as  the  stream  is  keeping 
the  pond  full. 

Your  weir  should  be  fashioned  with  the  idea 
of  some  permanency  so  that  a  number  of 
measurements  may  be  taken,  extending  over  a 
period  of  time — thus  enabling  the  prospector 
to  make  a  reliable  estimate  not  only  of  the 
amount  of  water  flowing  at  any  one  time,  but 
of  its  fluctuations. 

Under  expert  supervision,  this  simple  weir 
is  an  exact  contrivance — exact  enough,  in  fact, 
for  the  finest  calculations  required  in  engineer- 
ing work.  To  find  out  how  many  cubic  feet  of 
water  the  stream  is  delivering  at  any  moment, 
all  that  is  necessary  is  to  measure  its  depth 
where  it  flows  through  the  opening.  There  are 


HOW  TO  MEASURE  WATER-POWER      41 

instruments,  like  the  hook-gauge,  which  are 
designed  to  measure  this  depth  with  accuracy 
up  to  one-thousandth  of  an  inch.  An  ordinary 
foot  rule,  or  a  folding  rule,  will  give  results 
sufficiently  accurate  for  the  water  prospector 
in  this  instance.  The  depth  should  be  meas- 
ured not  at  the  opening  itself,  but  a  short 
distance  back  of  the  opening,  where  the  water 
is  setting  at  a  dead  level  and  is  moving  very 
slowly. 

With  this  weir,  every  square  inch  of  water 
flowing  through  the  opening  indicates  roughly 
one  cubic  foot  of  water  a  minute.  Thus  if  the 
opening  is  10  inches  wide  and  the  water  flow- 
ing through  it  is  5  inches  deep,  the  number  of 
cubic  feet  a  minute  the  stream  is  delivering 
is  10  x  5  =  50  square  inches  =  50  cubic  feet 
a  minute.  This  is  a  very  small  stream; 
yet,  if  it  could  be  made  to  fall  through  a 
water  wheel  10  feet  below  a  pond  or  reser- 
voir, it  would  exert  a  continuous  pressure 
of  30,000  pounds  per  minute  on  the  blades 
of  the  wheel — nearly  one  theoretical  horse- 
power. 


42  ELECTRICITY  FOR  THE  FARM 

This  estimate  of  one  cubic  foot  to  each 
square  inch  is  a  very  rough  approximation. 
Engineers  have  developed  many  complicated 
formulas  for  determining  the  flow  of  water 
through  weirs,  taking  into  account  fine  varia- 
tions that  the  farm  prospector  need  not  heed. 
The  so-called  Francis  formula,  developed  by 
a  long  series  of  actual  experiments  at  Lowell, 
Mass.,  in  1852  by  Mr.  James  B.  Francis,  with 
weirs  10  feet  long  and  5  feet  2  inches  high,  is 
standard  for  these  calculations  and  is  expressed 
(for  those  who  desire  to  use  it  for  special 
purposes)  as  follows  : 


Q  =  3.33  L  H    or,  Q  =  3.33  L 


in  which  Q  means  quantity  of  water  in 
cubic  feet  per  second,  L  is  length  of  open- 
ing, in  feet;  and  H  is  height  of  opening  in 
feet. 

The  following  table  is  figured  according  to 
the  Francis  formula,  and  gives  the  discharge 
in  cubic  feet  per  minute,  for  openings  one  inch 
wide: 


HOW  TO  MEASURE  WATER-POWER      43 
TABLE  OF  WEIRS 


Inchet 

1 

2 

3 

4 

5 

6 

7 

8 

9 
10 
11 
12 
13 
14 
15 
16 
17 
18 


Thus,  let  us  say,  our  weir  has  an  opening 
30  inches  wide,  and  the  water  overflows 
through  the  opening  at  a  uniform  depth  of 
6j^  inches,  when  measured  a  few  inches  be- 
hind the  board  at  a  point  before  the  overflow 
curve  begins.  Run  down  the  first  column 
on  the  left  to  "6",  and  cross  over  to  the 
second  column  to  the  right,  headed  "34"- 
This  gives  the  number  of  cubic  feet  per  min- 
ute for  this  depth  one  inch  wide,  as  6.298. 


0 

M 

^ 

M 

0.403 

0.563 

0.740 

0.966 

1.141 

1.360 

1.593 

1.838 

2.094 

2.361 

2.639 

2.927 

3.225 

3.531 

3.848 

4.173 

4.506 

4.849 

5.200 

5.558 

5.925 

6.298 

6.681 

7.071 

7.465 

7.869 

8.280 

8.697 

9.121 

9.552 

9.990 

10.427 

10.884 

11.340 

11.804 

12.272 

12.747 

13.228 

13.716 

14.208 

14.707 

15.211 

15.721 

16.236 

16.757 

17.283 

17.816 

18.352 

18.895 

19.445 

19.996 

20.558 

21.116 

21.684 

22.258 

22.835 

23.418 

24.007 

24.600 

25.195 

25.800 

26.406 

27.019 

27.634 

28.256 

28.881 

29.512 

30.145 

30.785 

31.429 

32.075 

32.733 

44          ELECTRICITY  FOR  THE  FARM 

Since  the  weir  is  30  inches  wide,  multiply 
6.298  x  30  =  188.94— or,  say,  189  cubic  feet 
per  minute. 

Once  the  weir  is  set,  it  is  the  work  of  but  a 
moment  to  find  out  the  quantity  of  water  a 
stream  is  delivering,  simply  by  referring  to 
the  above  table. 

Another  Method  of  Measuring  a  Stream 

Weirs  are  for  use  in  small  streams.  For 
larger  streams,  where  the  construction  of  a 
weir  would  be  difficult,  the  U.  S.  Geological 
Survey  engineers  recommend  the  following 
simple  method : 

Choose  a  place  where  the  channel  is  straight 
for  100  or  200  feet,  and  has  a  nearly  constant 
depth  and  width;  lay  off  on  the  bank  a  line 
50  or  100  feet  in  length.  Throw  small  chips 
into  the  stream,  and  measure  the  time  in 
seconds  they  take  to  travel  the  distance 
laid  off  on  the  bank.  This  gives  the  surface 
velocity  of  the  water.  Multiply  the  average 
of  several  such  tests  by  0.80,  which  will  give 
very  nearly  the  mean  velocity.  Then  it  is 


HOW  TO  MEASURE  WATER-POWER      45 

necessary  to  find  the  cross-section  of  the 
flowing  water  (its  average  depth  multiplied 
by  width),  and  this  number,  in  square  feet, 
multiplied  by  the  velocity  in  feet  per  second, 
will  give  the  number  of  cubic  feet  the  stream 
is  delivering  each  second.  Multiplied  by 
60  gives  cubic  feet  a  minute. 

Figuring  a  Stream9 s  Horsepower 

By  one  of  the  above  simple  methods,  the 
problem  of  Quantity  can  easily  be  determined. 
The  next  problem  is  to  determine  what  Head 
can  be  obtained.  Head  is  the  distance  in 
feet  the  water  may  be  made  to  fall,  from  the 
Source  of  Supply,  to  the  water  wheel  itself. 
The  power  of  water  is  directly  proportional 
to  head,  just  as  it  is  directly  proportional 
to  quantity.  Thus  the  typical  weir  measured 
above  was  30  inches  wide  and  6j^  deep, 
giving  189  cubic  feet  of  water  a  minute — 
Quantity.  Since  such  a  stream  is  of  common 
occurrence  on  thousands  of  farms,  let  us  an- 
alyze briefly  its  possibilities  for  power:  One 
hundred  and  eighty-nine  cubic  feet  of  water 


46 


ELECTRICITY  FOR  THE  FARM 


II 

r 

r   i    ^ 

~*M 

i%|^ 

2kj 

/  fe£M 

X   ly 

1 

/' 

ili 

1 

HOW  TO  MEASURE  WATER-POWER      47 

weighs  189  x  62.5  pounds  =  11,812.5  pounds. 
Drop  this  weight  one  foot,  and  we  have 
11,812.5  foot-pounds.  Drop  it  3  feet  and 
we  have  11,812  x  3  =  35,437.5  foot-pounds. 
Since  33,000  foot-pounds  exerted  in  one 
minute  is  one  horsepower,  we  have  here  a 
little  more  than  one  horsepower.  For  simplic- 
ity let  us  call  it  a  horsepower. 

Now,  since  the  work  to  be  had  from  this 
water  varies  directly  with  quantity  and  head, 
it  is  obvious  that  a  stream  one-half  as  big 
falling  twice  as  far,  would  still  give  one  horse- 
power at  the  wheel;  or,  a  stream  of  189  cubic 
feet  a  minute  falling  ten  times  as  far,  30  feet, 
would  give  ten  times  the  power,  or  ten  horse- 
power; a  stream  falling  one  hundred  times 
as  far  would  give  one  hundred  horsepower. 
Thus  small  quantities  of  water  falling  great 
distances,  or  large  quantities  of  water  falling 
small  distances  may  accomplish  the  same 
results.  From  this  it  will  be  seen,  that  the 
simple  formula  for  determining  the  theoreti- 
cal horsepower  of  any  stream,  in  which  Quan- 
tity and  Head  are  known,  is  as  follows: 


48          ELECTRICITY  FOR  THE  FARM 

Cu.  Ft.  per       Feet 

_.  minute      x  head  x  62.5 

(A)  Theoretical  Horsepower  = 

33,000 

As  an  example,  let  us  say  that  we  have  a  stream 
whose  weir  measurement  shows  it  capable  of 
delivering  376  cubic  feet  a  minute,  with  a  head 
(determined  by  survey)  of  13  feet  6  inches.  What 
is  the  horsepower  of  this  stream? 

Cu.  ft.  p.  m.   head     pounds 

Answer:  376     x  13-5  x  62-5 

TT  p   '  = =9. 6 14  horsepower 

H-  ^  33,000 

This  is  theoretical  horsepower.  To  determine 
the  actual  horsepower  that  can  be  counted 
on,  in  practice,  it  is  customary,  with  small 
water  wheels,  to  figure  25  per  cent  loss  through 
friction,  etc.  In  this  instance,  the  actual 
horsepower  would  then  be  7.2. 

The  Size  of  the  Wheel 

Water  wheels  are  not  rated  by  horsepower 
by  manufacturers,  because  the  same  wheel 
might  develop  one  horsepower  or  one  hundred 
horsepower,  or  even  a  thousand  horsepower, 


HOW  TO  MEASURE  WATER-POWER      49 

according  to  the  conditions  under  which  it 
is  used.  With  a  given  supply  of  water,  the 
head,  in  feet,  determines  the  size  of  wheel 
necessary.  The  farther  a  stream  of  water 
falls,  the  smaller  the  pipe  necessary  to  carry 
a  given  number  of  gallons  past  a  given  point 
in  a  given  time. 

A  small  wheel,  under  10  x  13.5  ft.  head, 
would  give  the  same  power  with  the  above 
376  cubic  feet  of  water  a  minute,  as  a  large 
wheel  would  with  10  x  376  cubic  feet,  under  a 
13.5  foot  head. 

This  is  due  to  the  acceleration  of  gravity 
on  falling  bodies.  A  rifle  bullet  shot  into 
the  air  with  a  muzzle  velocity  of  3,000  feet 
a  second  begins  to  diminish  its  speed  instantly 
on  leaving  the  muzzle,  and  continues  to  dim- 
inish in  speed  at  the  fixed  rate  of  32.16  feet  a 
second,  until  it  finally  comes  to  a  stop,  and 
starts  to  descend.  Then,  again,  its  speed 
accelerates  at  the  rate  of  32.16  feet  a  second, 
until  on  striking  the  earth  it  has  attained 
the  velocity  at  which  it  left  the  muzzle  of  the 
rifle,  less  loss  due  to  friction. 


50          ELECTRICITY  FOR  THE  FARM 

The  acceleration  of  gravity  affects  falling 
water  in  the  same  manner  as  it  affects  a  falling 
bullet.  At  any  one  second,  during  its  course 
of  fall,  it  is  traveling  at  a  rate  32.16  feet  a 
second  in  excess  of  its  speed  the  previous 
second. 

In  figuring  the  size  wheel  necessary  under 
given  conditions  or  to  determine  the  power 
of  water  with  a  given  nozzle  opening,  it  is 
necessary  to  take  this  into  account.  The 
table  on  page  51  gives  velocity  per  second  of 
falling  water,  ignoring  the  friction  of  the  pipe, 
in  heads  from  5  to  1000  feet. 

The  scientific  formula  from  which  the 
table  is  computed  is  expressed  as  follows,  for 
those  of  a  mathematical  turn  of  mind: 


Velocity  (ft.  per  sec.)  =  ^2gh;  or,  veloc- 
ity is  equal  to  the  square  root  of  the  product 
(g  =  32.16,  —  times  head  in  feet,  multiplied 

by  2). 

In  the  above  example,  we  found  that  376  cubic 
feet  of  water  a  minute,  under  13.5  feet  head, 
would  deliver  7.2  actual  horsepower.  Question: 


HOW  TO  MEASURE  WATER-POWER      51 

SPOUTING  VELOCITY  OF  WATER,  IN  FEET  PER  SECOND, 
IN  HEADS  OF  FROM  5  TO  1,000  FEET 

Head  Velodt, 

5 17.9 

6 19.7 

7 21.2 

8 22.7 

9 24.1 

10 25.4 

11 26.6 

11.5 27.2 

12 27.8 

12.5 28.4 

13 28.9 

13.5 29.5 

14 30.0 

14.5 30.5 

15 31.3 

15.5 31.6 

16 32.1 

16.5 32.6 

17 33.1 

17 . 5 33 . 6 

18 34.0 

18.5 34.5 

19 35.0 

19.5 35.4 

20 35.9 

20.5 36.3 

21 36.8 

21.5 37.2 

22 37.6 

22.5 38.1 

23 38.5 

23.5 38.9 

24 39.3 

24.5 39.7 

25 - 40.1 

26 40.9 

27 41.7 

28..  .  42.5 


Head 

Velocity 

29  

43.2 

30  

43.9 

31  

44.7 

32  

45.4 

33  

46.1 

34  

46.7 

35  

47.4 

36  

48.1 

37  

48.8 

38  

49.5 

39  

50.1 

40  

50.7 

41  

51.3 

42  

52.0 

43  

52.6 

44  

53.2 

45  

53.8 

46  

54.4 

47  

55.0 

48  

55.6 

49  

56  2 

50  

56.7 

55  

59.5 

60  

62.1 

65  

64.7 

70  

67.1 

75  

69.5 

80  

71.8 

85  

74.0 

90  

76.1 

95  

78.2 

100  

80.3 

200  

114.0 

300  

139.0 

400  

160.0 

500  

179.0 

1000  

254.0 

52  ELECTRICITY  FOR  THE  FARM 

What  size  wheel  would  it  be  necessary  to  install 
under  such  conditions? 

By  referring  to  the  table  of  velocity  above, 
(or  by  using  the  formula),  we  find  that  water 
under  a  head  of  13.5  feet,  has  a  spouting  veloc- 
ity of  29.5  feet  a  second.  This  means  that  a 
solid  stream  of  water  29.5  feet  long  would 
pass  through  the  wheel  in  one  second.  What 
should  be  the  diameter  of  such  a  stream,  to  make 
its  cubical  contents  376  cubic  feet  a  minute  or 
f|  =  6.27  cubic  feet  a  second?  The  following 
formula  should  be  used  to  determine  this: 


/T>\  o      T     t        s     i.    i       144  x  cu.  ft.  per  second 
(B)  Sq.  Inches  of  wheel  =  ^-, — ^7 — ; — -£- 

Velocity  in  ft.  per  sec. 


Substituting  values,  in  the  above  instance,  we 
have: 

Answer:  Sq.  Inches  of  wheel  = 

144  x  6.27  (Cu.  Ft.  Sec.)  _  30  6  SQ   in 
29.5  (Vel.  in  feet.) 

That  is,  a  wheel  capable  of  using  30.6 
square  inches  of  water  would  meet  these 
conditions. 


HOW  TO  MEASURE  WATER-POWER      53 

What  Head  is  Required 

Let  us  attack  the  problem  of  water-power  in 
another  way.  A  farmer  wishes  to  install  a 
water  wheel  that  will  deliver  10  horsepower  on  the 
shaft,  and  he  finds  his  stream  delivers  400  cubic 
feet  of  water  a  minute.  How  many  feet  fall  is 
required?  Formula : 

(C)  Head  in  feet  =  33,000  x  horsepower  required 
Cu.  Ft.  per  minute  x  62.5 

Since  a  theoretical  horsepower  is  only  75 
per  cent  efficient,  he  would  require  10  x  j  = 
13.33  theoretical  horsepower  of  water,  in  this 
instance.  Substituting  the  values  of  the 
problem  in  the  formula,  we  have: 


A  „      ,    33,000  x  13.33    ,_„.,,„          .     , 

Answer:  Head  =  — 77:7: — ^TTT~  =17.6  feet  fall  required. 
400  x  62.5 


What  capacity  of  wheel  would  this  prospect 
(400  cubic  feet  of  water  a  minute  falling  17.6 
feet,  and  developing  13.33  horsepower)  require? 

By  referring  to  the  table  of  velocities,  we 
find  that  the  velocity  for  17.5  feet  head 
(nearly)  is  33.6  feet  a  second.  Four  hundred 


54          ELECTRICITY  FOR  THE  FARM 

feet  of  water  a  minute  is  f^  =  6.67  cu.  ft.  a 
second.  Substituting  these  values,  in  formula 
(B)  then,  we  have: 

Answer:  Capacity  of  wheel  = 

144  x  6.67  .     ,         , 

— ==-= —  =  28.6  square  inches  of  water. 

'    OO.D 

Quantity  of  Water 

Let  us  take  still  another  problem  which  the 
prospector  may  be  called  on  to  solve:  A  man 
finds  that  he  can  conveniently  get  a  fall  of  27  feet. 
He  desires  20  actual  horsepower.  What  quantity 
of  water  will  be  necessary,  and  what  capacity 
wheel? 

Twenty  actual  horsepower  will  be  20  x  |  = 
26.67  theoretical  horsepower.  Formula: 

33,000  x  Hp.  required 
(D)  Cubic  feet  per  minute  =      Head  in  feet  x  62.5 

Substituting  values,  then,  we  have: 
Cu.  ft.  per  minute  = 

3%°7°°xX6f567=  521.5  cubic  feet  a  minute. 

A  head  of  27  feet  would  give  this  stream  a 
velocity  of  41.7  feet  a  second,  and,  from 


HOW  TO  MEASURE  WATER-POWER      55 

formula  (B)  we  find  that  the  capacity  of  the 
wheel  should  be  30  square  inches. 

It  is  well  to  remember  that  the  square 
inches  of  wheel  capacity  does  not  refer  to  the 
size  of  pipe  conveying  water  from  the  head  to 
the  wheel,  but  merely  to  the  actual  nozzle 
capacity  provided  by  the  wheel  itself.  In 
small  installations  of  low  head,  such  as  above 
a  penstock  at  least  six  times  the  nozzle  capac- 
ity should  be  used,  to  avoid  losing  effective 
head  from  friction.  Thus,  with  a  nozzle  of  30 
square  inches,  the  penstock  or  pipe  should  be 
180  square  inches,  or  nearly  14  inches  square 
inside  measurement.  A  larger  penstock  would 
be  still  better. 


CHAPTER  IV 

THE  WATER  WHEEL  AND  HOW  TO  INSTALL  IT 

Different  types  of  water  wheels — The  impulse  and 
reaction  wheels — The  impulse  wheel  adapted  to 
high  heads  and  small  amount  of  water — Pipe 
lines — Table  of  resistance  in  pipes — Advantages 
and  disadvantages  of  the  impulse  wheel — Other 
forms  of  impulse  wheels — The  reaction  turbine, 
suited  to  low  heads  and  large  quantity  of  water — 
Its  advantages  and  limitations — Developing  a 
water-power  project:  the  dam;  the  race;  the  flume; 
the  penstock;  and  the  tailrace — Water  rights  for 
the  farmer. 

IN  general,  there  are  two  types  of  water 
wheels,  the  impulse  wheel  and  the  reaction 
wheel.  Both  are  called  turbines,  although  the 
name  belongs,  more  properly,  to  the  reaction 
wheel  alone. 

Impulse  wheels  derive  their  power  from 
the  momentum  of  falling  water.  Reaction 
wheels  derive  their  power  from  the  momentum 
and  pressure  of  falling  water.  The  old- 
fashioned  undershot,  overshot,  and  breast  wheels 

56 


WATER  WHEEL,  HOW  TO  INSTALL  IT    57 

are  familiar  to  all  as  examples  of  impulse 
wheels.  Water  wheels  of  this  class  revolve  in 
the  air,  with  the  energy  of  the  water  exerted 
on  one  face  of  their  buckets.  On  the  other 
hand,  reaction  wheels  are  enclosed  in  water- 
tight cases,  either  of  metal  or  of  wood,  and  the 
buckets  are  entirely  surrounded  by  water. 

The  old-fashioned  undershot,  overshot,  and 
breast  wheels  were  not  very  efficient;  they 
wasted  about  75  per  cent  of  the  power  ap- 
plied to  them.  A  modern  impulse  wheel,  on 
the  other  hand,  operates  at  an  efficiency  of 
80  per  cent  and  over.  The  loss  is  mainly 
through  friction  and  leakage,  and  cannot  be 
eliminated  altogether.  The  modern  reaction 
wheel,  called  the  turbine,  attains  an  equal 
efficiency.  Individual  conditions  govern  the 
type  of  wheel  to  be  selected. 

The  Impulse,  or  Tangential  Water  Wheel 

The  modern  impulse,  or  tangential  wheel 
(so  called  because  the  driving  stream  of  water 
strikes  the  wheel  at  a  tangent)  is  best  adapted 
to  situations  where  the  amount  of  water  is 


58          ELECTRICITY  FOR  THE  FARM 

limited,  and  the  head  is  large.  Thus,  a  moun- 
tain brook  supplying  only  seven  cubic  feet 
of  water  a  minute — a  stream  less  than  two- 
and-a-half  inches  deep  flowing  over  a  weir  with 
an  opening  three  inches  wide — would  develop 
two  actual  horsepower,  under  a  head  of  200 
feet — not  an  unusual  head  to  be  found  in  the 
hill  country.  Under  a  head  of  one  thousand 
feet,  a  stream  furnishing  352.6  cubic  feet  of 
water  a  minute  would  develop  534.01  horse- 
power at  the  nozzle. 

Ordinarily  these  wheels  are  not  used  under 
heads  of  less  than  20  feet.  A  wheel  of  this 
type,  six  feet  in  diameter,  would  develop  six 
horsepower,  with  188  cubic  feet  of  water  a 
minute  and  20-foot  head.  The  great  majority 
of  impulse  wheels  are  used  under  heads  of  100 
feet  and  over.  In  this  country  the  greatest 
head  in  use  is  slightly  over  2,100  feet,  although 
in  Switzerland  there  is  one  plant  utilizing  a 
head  of  over  5,000  feet. 

The  old-fashioned  impulse  wheels  were 
inefficient  because  of  the  fact  that  their 
buckets  were  not  constructed  scientifically, 


Runner  of  Pelton  wheel,  showing  peculiar  shape  of  the  buckets 


The  Fitz  overshoot  wheel 


EFFICIENT   MODERN   ADAPTATIONS  OF  THE   ARCHAIC   UNDERSHOT 
AND  OVERSHOT  WATER  WHEEUS 


WATER  WHEEL,  HOW  TO  INSTALL  IT    59 

and  much  of  the  force  of  the  water  was  lost  at 
the  moment  of  impact.  .  The  impulse  wheel  of 
to-day,  however,  has  buckets  which  so  com- 
pletely absorb  the  momentum  of  water  issuing 
from  a  nozzle,  that  the  water  falls  into  the 
tailrace  with  practically  no  velocity.  When  it 
is  remembered  that  the  nozzle  pressure  under 
a  2,250-foot  head  is  nearly  1,000  pounds  to  the 
square  inch,  and  that  water  issues  from  this 
nozzle  with  a  velocity  of  23,000  feet  a  minute, 
the  scientific  precision  of  this  type  of  bucket 
can  be  appreciated. 

A  typical  bucket  for  such  a  wheel  is  shaped 
like  an  open  clam  shell,  the  central  line  which 
cuts  the  stream  of  water  into  halves  being 
ground  to  a  sharp  edge.  The  curves  which 
absorb  the  momentum  of  the  water  are 
figured  mathematically  and  in  practice  become 
polished  like  mirrors.  So  great  is  the  eroding 
action  of  water,  under  great  heads — especially 
when  it  contains  sand  or  silt — that  it  is  occa- 
sionally necessary  to  replace  these  buckets. 
For  this  reason  the  larger  wheels  consist 
merely  of  a  spider  of  iron  or  steel,  with  each 


60          ELECTRICITY  FOR  THE  FARM 

bucket  bolted  separately  to  its  circumference, 
so  that  it  can  be  removed  and  replaced  easily. 
Usually  only  one  nozzle  is  provided;  but  in 
order  to  use  this  wheel  under  low  heads — 
down  to  10  feet — a  number  of  nozzles  are  used, 
sometimes  five,  where  the  water  supply  is 
plentiful. 

The  wheel  is  keyed  to  a  horizontal  shaft 
running  in  babbited  bearings,  and  this  same 
shaft  is  used  for  driving  the  generator,  either 
by  direct  connection,  or  by  means  of  pulleys 
and  a  belt.  The  wheel  may  be  mounted  on  a 
home-made  timber  base,  or  on  an  iron  frame. 
It  takes  up  very  little  room,  especially  when 
it  is  so  set  that  the  nozzle  can  be  mounted 
under  the  flooring.  The  wheel  itself  is  en- 
closed, above  the  floor,  in  a  wooden  box,  or  a 
casing  made  of  cast  or  sheet  iron,  which  should 
be  water-tight. 

Since  these  wheels  are  usually  operated 
under  great  heads,  the  problem  of  regulating 
their  water  supply  requires  special  considera- 
tion. A  gate  is  always  provided  at  the  upper, 
or  intake  end,  where  the  water  pipe  leaves  the 


WATER  WHEEL,  HOW  TO  INSTALL  IT    61 

flume.  Since  the  pressure  reaches  1,000 
pounds  the  square  inch  and  more,  there  would 
be  danger  of  bursting  the  pipe  if  the  water 
were  suddenly  shut  off  at  the  nozzle  itself. 
For  this  reason  it  is  necessary  to  use  a  needle 
valve,  similar  to  that  in  an  ordinary  garden 
hose  nozzle;  and  by  such  a  valve  the  amount 
of  water  may  be  regulated  to  a  nicety.  Where 
the  head  is  so  great  that  even  such  a  valve 
could  not  be  used  safely,  provision  is  made 
to  deflect  the  nozzle.  These  wheels  have 
a  speed  variation  amounting  to  as  much  as 
25  per  cent  from  no-load  to  full  load,  in  gen- 
erating electricity,  and  since  the  speed  of  the 
prime  mover — the  water  wheel — is  reflected 
directly  in  the  voltage  or  pressure  of  electricity 
delivered,  the  wheel  must  be  provided  with 
some  form  of  automatic  governor.  This  con- 
sists usually  of  two  centrifugal  balls,  similar  to 
those  used  in  governing  steam  engines;  these 
are  connected  by  means  of  gears  to  the  needle 
valve  or  the  deflector. 

As  the  demand  for  farm  water-powers  in 
our  hill  sections  becomes  more  general,  the 


62          ELECTRICITY  FOR  THE  FARM 

tangential  type  of  water  wheel  will  come  into 
common  use  for  small  plants.  At  present  it 
is  most  familiar  in  the  great  commercial  in- 
stallations of  the  Far  West,  working  under 
enormous  heads.  These  wheels  are  to  be  had 
in  the  market  ranging  in  size  from  six  inches  to 
six  feet  and  over.  Wheels  ranging  in  size  from 
six  inches  to  twenty-four  inches  are  called 
water  motors,  and  are  to  be  had  in  the  market, 
new,  for  $30  for  the  smallest  size,  and  $275 
for  the  largest.  Above  three  feet  in  diameter, 
the  list  prices  will  run  from  $200  for  a  3 -foot 
wheel  to  $800  for  a  6 -foot  wheel.  Where  one 
has  a  surplus  of  water,  it  is  possible  to  install  a 
multiple  nozzle  wheel,  under  heads  of  from 
10  to  100  feet,  the  cost  for  18-inch  wheels  of 
this  pattern  running  from  $150  to  $180  list, 
and  for  24-inch  wheels  from  $200  to  $250. 
A  24-inch  wheel,  with  a  10-foot  head  would 
give  1.19  horsepower,  enough  for  lighting  the 
home,  and  using  an  electric  iron.  Under  a 
100-foot  head  this  same  wheel  would  provide 
25.9  horsepower,  to  meet  the  requirements  of 
a  bigger-than-average  farm  plant. 


WATER  WHEEL,  HOW  TO  INSTALL  IT    63 

The  Pipe  Line 

The  principal  items  of  cost  in  installing  an 
impulse  wheel  are  in  connection  with  the  pipe 
line,  and  the  governor.  In  small  heads,  that 
is,  under  100  feet,  the  expense  of  pipe  line  is 
low.  Frequently,  however,  the  governor  will 
cost  more  than  the  water  motor  itself,  although 
cheaper,  yet  efficient,  makes  are  now  being 
put  on  the  market  to  meet  this  objection.  In  a 
later  chapter,  we  will  take  up  in  detail  the 
question  of  governing  the  water  wheel,  and 
voltage  regulation,  and  will  attempt  to  show 
how  this  expense  may  be  practically  eliminated 
by  the  farmer. 

To  secure  large  heads,  it  is  usually  necessary 
to  run  a  pipe  line  many  hundreds  (and  in  many 
cases,  many  thousands)  of  feet  from  the  flume 
to  the  water  wheel.  Water  flowing  through 
pipes  is  subject  to  loss  of  head,  by  friction,  and 
for  this  reason  the  larger  the  pipe  the  less  the 
friction  loss.  Under  no  circumstances  is  it 
recommended  to  use  a  pipe  of  less  than  two 
inches  in  diameter,  even  for  the  smallest  water 


64          ELECTRICITY  FOR  THE  FARM 

motors;  and  with  a  two-inch  pipe,  the  run 
should  not  exceed  200  feet.  Where  heavy- 
pressure  mains,  such  as  those  of  municipal  or 
commercial  water  systems,  are  available,  the 
problem  of  both  water  supply  and  head 
becomes  very  simple.  Merely  ascertain  the 
pressure  of  the  water  in  the  mains  when  flowing, 
determine  the  amount  of  power  required  (as 
illustrated  in  a  succeeding  chapter  of  this 
book),  and  install  the  proper  water  motor  with 
a  suitably  sized  pipe. 

Where  one  has  his  own  water  supply,  how- 
ever, and  it  is  necessary  to  lay  pipe  to  secure 
the  requisite  fall,  the  problem  is  more  difficult. 
Friction  in  pipes  acts  in  the  same  way  as  cut- 
ting down  the  head  a  proportional  amount; 
and  by  cutting  down  the  head,  your  water 
motor  loses  power  in  direct  proportion  to  the 
number  of  feet  head  lost.  This  head,  obtained 
by  subtracting  friction  and  other  losses  from 
the  surveyed  head,  is  called  the  effective  head, 
and  determines  the  amount  of  power  delivered 
at  the  nozzle. 

The  tables  on  pages  66-67  show  the  friction 


WATER  WHEEL,  HOW  TO  INSTALL  IT    65 

loss  in  pipes  up  to  12  inches  in  diameter,  ac- 
cording to  the  amount  of  water,  and  the  length 
of  pipe. 

In  this  example  it  is  seen  that  a  240-foot 
static  head  is  reduced  by  friction  to  230.1 
feet  effective  head.  By  referring  to  the  table 
we  find  the  wheel  fitting  these  conditions  has 
a  nozzle  so  small  that  it  cuts  down  the  rate 
of  flow  of  water  in  the  big  pipe  to  4.4  feet 
a  second,  and  permits  the  flow  of  only  207 
cubic  feet  of  water  a  minute.  The  actual 
horsepower  of  this  tube  and  nozzle,  then, 
can  be  figured  by  applying  formula  (A), 
Chapter  III,  allowing  80  per  cent  for  the 
efficiency  of  the  wheel.  Thus: 

Actual  horsepower  = 

•"•1  •" 


.  • 

To  calculate  what  the  horsepower  of  this 
tube  12  inches  in  diameter  and  900  feet  long, 
would  be  without  a  nozzle,  under  a  head  of 
240  feet,  introduces  a  new  element  of  friction 
losses,  which  is  too  complicated  to  figure 
here.  Such  a  condition  would  not  be  met 


66  ELECTRICITY  FOR  THE  FARM 


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WATER  WHEEL,  HOW  TO  INSTALL  IT        67 


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68  ELECTRICITY  FOR  THE  FARM 

with  in  actual  practice,  in  any  event.  The 
largest  nozzles  used,  even  in  the  jumbo  plants 
of  the  Far  West,  rarely  exceed  10  inches  in 
diameter;  and  the  pipe  conveying  water  to 
such  a  nozzle  is  upwards  of  eight  feet  in  diame- 
ter. 

Steel  tubing  for  supply  pipes,  from  3  to  12 
inches  in  diameter  is  listed  at  from  20  cents 
to  $1.50  a  foot,  according  to  the  diameter 
and  thickness  of  the  material.  Discounts 
on  these  prices  will  vary  from  25  to  50  per 
cent.  The  farmer  can  cut  down  the  cost 
of  this  pipe  by  conveying  his  supply  water 
from  its  natural  source  to  a  pond,  by  means 
of  an  open  race,  or  a  wooden  flume.  An  in- 
genious mechanic  can  even  construct  his  own 
pipe  out  of  wood,  though  figuring  labor  and 
materials,  it  is  doubtful  if  anything  would 
be  saved  over  a  riveted  steel  pipe,  purchased 
at  the  regular  price.  This  pipe,  leading  from 
the  pond,  or  forebay,  to  the  water  wheel, 
should  be  kept  as  short  as  possible;  at  the 
same  time,  the  fall  should  not  be  too  sharp. 
An  angle  of  30°  will  be  found  very  satisfac- 


WATER  WHEEL,  HOW  TO  INSTALL  IT    69 

tory,    although    pipe    is    frequently    laid    at 
angles  up  to  50°. 

Other  Types  of  Impulse  Wheels 

In  recent  years  more  efficient  forms  of  the 
old-fashioned  overshoot,  pitch-back  breast, 
and  undershoot  wheels  have  been  developed, 
by  substituting  steel  or  other  metal  for  wood, 
and  altering  the  shape  of  the  buckets  to  make 
better  use  of  the  power  of  falling  water. 

In  some  forms  of  overshoot  wheels,  an 
efficiency  of  over  90  per  cent  is  claimed  by 
manufacturers;  and  this  type  offers  the  addi- 
tional advantage  of  utilizing  small  quantities 
of  water,  as  well  as  being  efficient  under 
varying  quantities  of  water.  They  utilize 
the  falling  weight  of  water,  although  by  giving 
the  water  momentum  at  the  point  of  delivery, 
by  means  of  the  proper  fall,  impulse  too  is 
utilized  in  some  measure.  The  modern  steel 
overshoot  wheel  receives  water  in  its  buckets 
from  a  spout  set  a  few  degrees  back  of 
dead  center;  and  its  buckets  are  so  shaped 
that  the  water  is  retained  a  full  half- 


70          ELECTRICITY  FOR  THE  FARM 

revolution  of  the  wheel.  The  old-style  over- 
shoot wheel  was  inefficient  principally  be- 
cause the  buckets  began  emptying  themselves 
at  the  end  of  a  quarter-revolution.  An- 
other advantage  claimed  for  these  wheels 
over  the  old  style  is  that,  being  made  of  thin 
metal,  their  buckets  attain  the  tempera- 
ture of  the  water  itself,  thus  reducing  the 
danger  of  freezing  to  a  minimum.  They  are 
manufactured  in  sizes  from  6  feet  in  diameter 
to  upwards  of  fifty  feet;  and  with  buckets  of 
from  6  inches  to  10  feet  in  width.  In  prac- 
tice it  is  usual  to  deliver  water  to  the  buckets 
by  means  of  a  trough  or  pipe,  through  a  suit- 
able spout  and  gate,  at  a  point  two  feet  above 
the  crown  of  the  wheel.  For  this  reason, 
the  diameter  of  the  wheel  corresponds  very 
closely  to  the  head  in  feet. 

The  Reaction  Turbine 

The  reaction  turbine  is  best  adapted  to 
low  heads,  with  a  large  supply  of  water.  It 
is  not  advisable,  under  ordinary  circumstances, 
to  use  it  under  heads  exceeding  100  feet,  as 


WATER  WHEEL,  HOW  TO  INSTALL  IT      71 

its  speed  is  then  excessive.  It  may  be  used 
under  falls  as  low  as  two  feet.  Five  thousand 
cubic  feet  of  water  a  minute  would  give  ap- 
proximately 14  actual  horsepower  under  such 
a  head.  A  sluggish  creek  that  flows  in  large 
volume  could  thus  be  utilized  for  power  with 
the  reaction  turbine,  whereas  it  would  be 
useless  with  an  impulse  wheel.  Falls  of  from 
five  to  fifteen  feet  are  to  be  found  on  thousands 
of  farm  streams,  and  the  reaction  turbine  is 
admirably  adapted  to  them. 

Reaction  turbines  consist  of  an  iron  "run- 
ner" which  is  in  effect  a  rotary  fan,  the  pres- 
sure and  momentum  of  the  column  of  water 
pressing  on  the  slanted  blades  giving  it  motion 
and  power.  These  wheels  are  manufactured 
in  a  great  variety  of  forms  and  sizes;  and  are 
to  be  purchased  either  as  the  runner  (set  in 
bearings)  alone,  or  as  a  runner  enclosed  in 
an  iron  case.  In  case  the  runner  alone  is  pur- 
chased, the  owner  must  enclose  it,  either  with 
iron  or  wood.  They  vary  in  price  according 
to  size,  and  the  means  by  which  the  flow  of 
water  is  controlled.  A  simple  12-inch  reaction 


72          ELECTRICITY  FOR  THE  FARM 

turbine  wheel,  such  as  would  be  suitable 
for  many  power  plants  can  be  had  for  $75. 
A  twelve-inch  wheel,  using  18  or  20  square 
inches  of  water,  would  generate  about  7J^ 
horsepower  under  a  20-foot  head,  with  268 
cubic  feet  of  water  a  minute.  Under  a  30- 
foot  head,  and  with  330  cubic  feet  of  water 
such  a  wheel  will  give  14  horsepower.  A 
36-inch  wheel,  under  a  5-foot  head,  would 
use  2,000  cubic  feet  of  water,  and  give  14 
horsepower.  Under  a  30-foot  head,  this 
same  wheel,  using  4,900  cubic  feet  of  water 
a  minute,  would  develop  over  200  horse- 
power. If  the  farmer  is  confronted  by  the 
situation  of  a  great  deal  of  water  and  small 
head,  a  large  wheel  would  be  necessary.  Thus 
he  could  secure  35  horsepower  with  only  a 
3 -foot  head,  providing  his  water  supply  is 
equal  to  the  draft  of  8,300  cubic  feet  a  minute. 
From  these  sample  figures,  it  will  be  seen 
that  the  reaction  turbine  will  meet  the  re- 
quirements of  widely  varying  conditions  up 
to,  say  a  head  of  100  feet.  The  farmer  pros- 
pector should  measure  first  the  quantity  of 


WATER  WHEEL,  HOW  TO  INSTALL  IT    73 


A  typical  vertical  turbine 


74          ELECTRICITY  FOR  THE  FARM 

water  to  be  depended  on,  and  then  the  num- 
ber of  feet  fall  to  be  had.  The  higher  the 
fall,  with  certain  limits,  the  smaller  the  ex- 
pense of  installation,  and  the  less  water  re- 
quired. When  he  has  determined  quantity 
and  head,  the  catalogue  of  a  reputable  manu- 
facturer will  supply  him  with  what  informa- 
tion is  necessary  to  decide  on  the  style  and 
size  wheel  he  should  install.  In  the  older 
settled  communities,  especially  in  New  Eng- 
land, a  farmer  should  be  able  to  pick  up  a 
second-hand  turbine,  at  half  the  price  asked 
for  a  new  one;  and  since  these  wheels  do  not 
depreciate  rapidly,  it  would  serve  his  purpose 
as  well,  in  most  cases,  as  a  new  one. 

Reaction  turbines  may  be  either  horizon- 
tal or  vertical.  If  they  are  vertical,  it  is 
necessary  to  connect  them  to  the  main  shaft 
by  means  of  a  set  of  bevel  gears.  These  gears 
should  be  substantially  large,  and  if  the  teeth 
are  of  hard  wood  (set  in  such  a  manner  that 
they  can  be  replaced  when  worn)  they  will 
be  found  more  satisfactory  than  if  of  cast 
or  cut  metal. 


WATER  WHEEL,  HOW  TO  INSTALL  IT    75 

The  horizontal  turbine  is  keyed  to  its 
shaft,  like  the  impulse  wheel,  so  that  the  wheel 
shaft  itself  is  used  for  driving,  without  gears 
or  a  quarter-turn  belt.  (The  latter  is  to  be 
avoided,  wherever  possible.)  There  are  many 
forms  of  horizontal  turbines;  they  are  to  be 
had  of  the  duplex  type,  that  is,  two  wheels 
on  one  shaft.  These  are  arranged  so  that 


Two  wheels  on  a  horizontal  shaft 
(Courtesy  of  the  C.  P.  Bradway  Company,  West  Stafford,  Conn.) 

either  wheel  may  be  run  separately,  or  both 
together,  thus  permitting  one  to  take  advan- 
tage of  the  seasonal  fluctuation  in  water 
supply.  A  convenient  form  of  these  wheels 
includes  draft  tubes,  by  which  the  wheel 
may  be  set  several  feet  above  the  tailrace, 
and  the  advantage  of  this  additional  fall  still 
be  preserved.  In  this  case  the  draft  tube 
must  be  airtight  so  as  to  form  suction,  when 


76          ELECTRICITY  FOR  THE  FARM 

filled  with  escaping  water,  and  should  be  pro- 
portioned to  the  size  of  the  wheel.  Theo- 
retically these  draft  tubes  might  be  34  feet 
long,  but  in  practice  it  has  been  found  that 
they  should  not  exceed  10  or  12  feet  under 
ordinary  circumstances.  They  permit  the 
wheel  to  be  installed  on  the  main  floor  of  the 
power  station,  with  the  escape  below,  instead 
of  being  set  just  above  the  tailrace  level  itself, 
as  is  the  case  when  draft  tubes  are  not  used. 

Reaction  turbines  when  working  under  a 
variable  load  require  water  governors  (like 
impulse  wheels)  although  where  the  supply  of 
water  is  large,  and  the  proportion  of  power 
between  water  wheel  and  dynamo  is  liberal — 
say  two  to  one,  or  more — this  necessity  is 
greatly  reduced.  Reaction  wheels  as  a  rule 
govern  themselves  better  than  impulse  wheels, 
due  both  to  the  fact  that  they  use  more  water, 
and  that  they  operate  in  a  small  airtight  case. 
The  centrifugal  ball  governor  is  the  type 
usually  used  with  reaction  wheels  as  well  as 
with  impulse  wheels.  This  subject  will  be 
discussed  more  fully  later. 


WATER  WHEEL,  HOW  TO  INSTALL  IT    77 

Installing  a  Power  Plant 

In  developing  a  power  prospect,  the  dam 
itself  is  usually  not  the  site  of  the  power  plant. 
In  fact,  because  of  danger  from  flood  water 
and  ice,  it  is  better  to  locate  it  in  a  more  pro- 
tected spot,  leading  the  water  to  the  wheel  by 
means  of  a  race  and  flume. 

A  typical  crib  dam,  filled  with  stone,  is 
shown  in  section  in  the  diagram,  and  the 
half-tone  illustration  shows  such  a  dam  hi 
course  of  construction.  The  first  bed  of  tim- 
bers should  be  laid  on  hard-pan  or  solid  rock 
in  the  bed  of  the  stream  parallel  to  its  flow. 
The  second  course,  across  the  stream,  is  then 
begun,  being  spiked  home  by  means  of  rods 
cut  to  length  and  sharpened  by  the  local 
blacksmith,  from  %-inch  Norway  iron.  Hem- 
lock logs  are  suitable  for  building  the  crib; 
and  as  the  timbers  are  finally  laid,  it  should 
be  filled  in  and  made  solid  with  boulders. 
This  filling  in  should  proceed  section  by 
section,  as  the  planking  goes  forward,  other- 
wise there  will  be  no  escape  for  the  water  of  the 


78 


ELECTRICITY  FOR  THE  FARM 


WATER  WHEEL,  HOW  TO  INSTALL  IT    79 

stream,  until  it  rises  and  spills  over  the  top 
timbers.  The  planking  should  be  of  two-inch 
chestnut,  spiked  home  with  60  penny  wire 
spikes.  When  the  last  section  of  the  crib  is 
filled  with  boulders  and  the  water  rises,  the 
remaining  planks  may  be  spiked  home  with 
the  aid  of  an  iron  pipe  in  which  to  drive  the 


KIVER  BED  SILT 

A  A  A-  HEMLOCK  LOGS  PARALLEL,  TO  FLOW  Of  STREAM 
BBS- HEM  LOCK  LOGS  ACROSS  FLOW  Of -STAEAft 
CC--  £.' CHESTNUT  PLAlVKLPfO 
EBE  ~  BOWLDERS    JJESTE&  2N   LO&   CKJ3 

Cross-section  of  a  rock  and  timber  dam 

spike  by  means  of  a  plunger  of  iron  long 
enough  to  reach  above  the  level  of  the  water. 
When  the  planking  is  completed,  the  dam 
should  be  well  gravelled,  to  within  a  foot  or 
two  of  its  crest.  Such  dams  are  substantial, 
easily  made  with  the  aid  of  unskilled  labor,  and 
the  materials  are  to  be  had  on  the  average 
farm  with  the  exception  of  the  hardware. 
This  dam  forms  a  pond  from  which  the  race 


80          ELECTRICITY  FOR  THE  FARM 

draws  its  supply  of  water  for  the  wheel.  It 
also  serves  as  a  spillway  over  which  the  surplus 
water  escapes.  The  race  should  enter  the 
pond  at  some  convenient  point,  and  should  be 
protected  at  or  near  its  point  of  entrance  by 
a  bulkhead  containing  a  gate,  so  that  the 
supply  of  water  may  be  cut  off  from  the  race 
and  wheel  readily.  The  lay  of  the  land  will 
determine  the  length  and  course  of  the  race. 
The  object  of  the  race  is  to  secure  the  re- 
quired head  by  carrying  a  portion  of  the 
available  water  to  a  point  where  it  can  escape, 
by  a  fall  of  say  30°  to  the  tailrace.  It  may  be 
feasible  to  carry  the  race  in  a  line  almost  at 
right  angles  to  the  stream  itself,  or,  again,  it 
may  be  necessary  to  parallel  the  stream.  If 
the  lay  of  the  land  is  favorable,  the  race  may 
be  dug  to  a  distance  of  a  rod  or  so  inshore,  and 
then  be  permitted  to  cut  its  own  course  along 
the  bank,  preventing  the  water  escaping  back 
to  the  river  or  brook  before  the  site  of  the 
power  plant  is  reached,  by  building  suitable 
retaining  embankments.  The  race  should  be 
of  ample  size  for  conveying  the  water  required 


WATER  WHEEL,  HOW  TO  INSTALL  IT    81 


without  too  much  friction.  It  should  end  in  a 
flume  constructed  stoutly  of  timbers.  It  is 
from  this  flume  that  the  penstock  draws  water 
for  the  wheel.  When  the  wheel  gate  is  closed 
the  water  in  the  mill  pond  behind  the  dam, 
and  in  the  flume  itself  should  maintain  an 
approximate  level.  Any  surplus  flow  is  per- 
mitted to  escape  over  flushboards  in  the 
flume;  these  same 
flushboards  main- 
tain a  constant 
head  when  the 
wheel  is  in  opera- 
tion by  carrying 
off  what  little  sur- 
plus water  the 
race  delivers  from 
the  pond. 

At  some  point 

in      tne      race      Or  # A -MUDSILLS -SUNK FLUSH wrm 'BED OF 'RACE 

SB  —  END  PLANKING 

flnrn*>  \\\C»         flrVO/    C  C  ~  PLAMONG  UALHW  DOWN  IftSltE  OF  GATE  SLOT 

I1UII1C,          LilC         IIUW     O    -GATE  W~  WATER  CHANNEL 

Should       be      pro-  Detail  of  bulkhead  gate 

tected  from  leaves  and  other  trash  by  means 
of  a  rack.    This  rack  is  best  made  of  \4  or 


82  ELECTRICITY  FOR  THE  FARM 


i/2-inch  battens  from  1J^  to  3  inches  in 
width,  bolted  together  on  their  flat  faces 
and  separated  a  distance  equal  to  the  thick- 
ness of  the  battens  by  means  of  iron  washers. 
This  rack  will  accumulate  leaves  and  trash, 
varying  with  the  time  of  year  and  should 
be  kept  clean,  so  as  not  to  cut  down  the 
supply  of  water  needed  by  the  wheel. 

The  penstock,  or  pipe  conveying  water  from 
the  flume  to  the  wheel,  should  be  constructed 
of  liberal  size,  and  substantially,  of  two-inch 
chestnut  planking,  with  joints  caulked  with 
oakum,  and  the  whole  well  bound  together  to 
resist  the  pressure  of  the  water.  Means  should 
be  provided  near  the  bottom  for  an  opening 
through  which  to  remove  any  obstructions 
that  may  by  accident  pass  by  the  rack.  Many 
wheels  have  plates  provided  in  their  cases  for 
this  purpose. 

The  tailrace  should  be  provided  with  enough 
fall  to  carry  the  escaping  water  back  to  the 
main  stream,  without  backing  up  on  the 
wheel  itself  and  thus  cutting  down  the  head. 

It  is  impossible  to  make  any  estimates  of  the 


WATER  WHEEL,  HOW  TO  INSTALL  IT    83 

cost  of  such  a  water-power  plant.  The  labor 
required  will  in  most  instances  be  supplied  by 
the  farmer  himself,  his  sons,  and  his  help, 
during  times  when  farm  operations  are  slack. 

Water  Rights  of  the  Farmer 

The  farmer  owns  the  bed  of  every  stream 
not  navigable,  lying  within  the  boundary 
lines  of  the  farm;  and  his  right  to  divert  and 
make  use  of  the  water  of  such  streams  is 
determined  in  most  states  by  common  law. 
In  the  dry-land  states  where  water  is  scarce 
and  is  valuable  for  irrigation,  a  special  set  of 
statutes  has  sprung  up  with  the  development 
of  irrigation  in  this  country. 

A  stream  on  the  farm  is  either  public  or 
private;  its  being  navigable  or  "floatable" 
(suitable  for  floating  logs)  determining  which. 
Water  rights  are  termed  in  law  "riparian" 
rights,  and  land  is  riparian  only  when  water 
flows  over  it  or  along  its  borders. 

Green  (Law  for  the  American  Farmer)  says : 

"  Water  is  the  common  and  equal  property 
of  every  one  through  whose  land  it  flows, 


84          ELECTRICITY  FOR  THE  FARM 

and  the  right  of  each  land-owner  to  use  and 
consume  it  without  destroying,  or  unreason- 
ably impairing  the  rights  of  others,  is  the 
same.  An  owner  of  land  bordering  on  a  run- 
ning stream  has  the  right  to  have  its  waters 
flow  naturally,  and  none  can  lawfully  divert 
them  without  his  consent.  Each  riparian 
proprietor  has  an  equal  right  with  all  the  others 
to  have  the  stream  flow  in  its  natural  way 
without  substantial  reduction  in  volume,  or 
deterioration  in  quality,  subject  to  a  proper 
and  reasonable  use  of  its  waters  for  domestic, 
agricultural  and  manufacturing  purposes,  and 
he  is  entitled  to  use  it  himself  for  such  pur- 
poses, but  in  doing  so  must  not  substantially 
injure  others.  In  addition  to  the  right  of 
drawing  water  for  the  purposes  just  men- 
tioned, a  riparian  proprietor,  if  he  duly  re- 
gards the  rights  of  others,  and  does  not  un- 
reasonably deplete  the  supply,  has  also  the 
right  to  take  the  water  for  some  other  proper 


uses." 


Thus,  the  farmer  who  seeks  to  develop  water- 
power  from  a  stream  flowing  across  his  own 


WATER  WHEEL,  HOW  TO  INSTALL  IT    85 

land,  has  the  right  to  divert  such  a  stream 
from  its  natural  channel — providing  it  is 
not  a  navigable  or  floatable  stream — but  in 
so  doing,  he  must  return  it  to  its  own  channel 
for  lower  riparian  owners.  The  generation 
of  water-power  does  not  pollute  the  water, 
nor  does  it  diminish  the  water  in  quantity, 
therefore  the  farmer  is  infringing  on  no  other 
owner's  rights  in  using  the  water  for  such  a 
purpose. 

When  a  stream  is  a  dividing  line  between 
two  farms,  as  is  frequently  the  case,  each 
proprietor  owns  to  the  middle  of  the  stream 
and  controls  its  banks.  Therefore  to  erect 
a  dam  across  such  a  private  stream  and  divert 
all  or  a  part  of  the  water  for  power  purposes, 
requires  the  consent  of  the  neighboring  owner. 
The  owner  of  the  dam  is  responsible  for  dam- 
age due  to  flooding,  to  upstream  riparian 
owners. 


PART  H 
ELECTRICITY 


CHAPTER  V 
THE  DYNAMO;  WHAT  IT  DOES,  AND  HOW 

Electricity  compared  to  the  heat  and  light  of  the  Sun 
—The  simple  dynamo — The  amount  of  electric 
energy  a  dynamo  will  generate — The  modern 
dynamo — Measuring  power  in  terms  of  electric- 
ity—The volt— The  ampere— The  ohm— The  watt 
and  the  kilowatt — Ohm's  Law  of  the  electric 
circuit,  and  some  examples  of  its  application — 
Direct  current,  and  alternating  current — Three 
types  of  direct-current  dynamos:  series,  shunt, 
and  compound. 

WHAT  a  farmer  really  does  in  generating 
electricity  from  water  that  would  otherwise 
run  to  waste  in  his  brook,  is  to  install  a  private 
Sun  of  his  own — which  is  on  duty  not  merely 
in  daylight,  but  twenty-four  hours  a  day;  a 
private  Sun  which  is  under  such  simple  con- 
trol that  it  shines  or  provides  heat  and  power, 
when  and  where  wanted,  simply  by  touching 
a  button. 

This  is  not  a  mere  fanciful  statement. 
When  you  come  to  look  into  it  you  find  that 


90  ELECTRICITY  FOR  THE  FARM 

electricity  actually  is  the  life-giving  power  of 
the  Sun's  rays,  so  transformed  that  it  can  be 
handily  conveyed  from  place  to  place  by  means 
of  wires,  and  controlled  by  mechanical  devices 
as  simple  as  the  spigot  that  drains  a  cask. 

Nature  has  the  habit  of  traveling  in  circles. 
Sometimes  these  circles  are  so  big  that  the 
part  of  them  we  see  looks  like  a  straight  line, 
but  it  is  not.  Even  parallel  lines,  according 
to  the  mathematicians,  "meet  in  infinity." 
Take  the  instance  of  the  water  wheel  which 
the  farmer  has  installed  under  the  fall  of  his 
brook.  The  power  which  turns  the  wheel  has 
the  strength  of  many  horses.  It  is  there  in  a 
handy  place  for  use,  because  the  Sun  brought 
it  there.  The  Sun,  by  its  heat,  lifted  the  water 
from  sea-level,  to  the  pond  where  we  find  it— 
and  we  cannot  get  any  more  power  out  of  this 
water  by  means  of  a  turbine  using  its  pressure 
and  momentum  in  falling,  than  the  Sun  itself 
expended  in  raising  the  water  against  the 
force  of  gravity. 

Once  we  have  installed  the  wheel  to  change 
the  energy  of  falling  water  into  mechanical 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    91 

power,  the  task  of  the  dynamo  is  to  turn  this 
mechanical  power  into  another  mode  of  mo- 
tion— electricity.  And  the  task  of  electricity 
is  to  change  this  mode  of  motion  back  into 
the  original  heat  and  light  of  the  Sun — which 
started  the  circle  in  the  beginning. 

Astronomers  refer  to  the  Sun  as  "he"  and 
"him"  and  they  spell  his  name  with  a  capital 
letter,  to  show  that  he  occupies  the  center  of 
our  small  neighborhood  of  the  universe  at 
all  times. 

Magnets  and  Magnetism 

The  dynamo  is  a  mechanical  engine,  like 
the  steam  engine,  the  water  turbine  or  the  gas 
engine;  and  it  converts  the  mechanical  motion 
of  the  driven  wheel  into  electrical  motion, 
with  the  aid  of  a  magnet.  Many  scientists 
say  that  the  full  circle  of  energy  that  keeps 
the  world  spinning,  grows  crops,  and  paints 
the  sky  with  the  Aurora  Borealis,  begins  and 
ends  with  magnetism — that  the  sun's  rays 
are  magnetic  rays.  Magnetism  is  the  force 
that  keeps  the  compass  needle  pointing  north 


92          ELECTRICITY  FOR  THE  FARM 

and  south.  Take  a  steel  rod  and  hold  it 
along  the  north  and  south  line,  slightly  inclined 
towards  the  earth,  and  strike  it  a  sharp  blow 
with  a  hammer,  and  it  becomes  a  magnet — 
feeble,  it  is  true,  but  still  a  magnet. 

Take  a  wire  connected  with  a  common  dry 
battery  and  hold  a  compass  needle  under  it 
and  the  needle  will  immediately  turn  around 
and  point  directly  across  the  wire,  showing 
that  the  wire  possesses  magnetism  encircling 
it  in  invisible  lines,  stronger  than  the  mag- 
netism of  the  earth. 

Insulate  this  wire  by  covering  it  with  cotton 
thread,  and  wind  it  closely  on  a  spool.  Con- 
nect the  two  loose  ends  to  a  dry  battery,  and 
you  will  find  that  you  have  multiplied  the 
magnetic  strength  of  a  single  loop  of  wire  by 
the  number  of  turns  on  the  spool — concen- 
trated all  the  magnetism  of  the  length  of  that 
wire  into  a  small  space.  Put  an  iron  core  in 
the  middle  of  this  spool  and  the  magnet  seems 
still  more  powerful.  Lines  of  force  which 
otherwise  would  escape  in  great  circles  into 
space,  are  now  concentrated  in  the  iron.  The 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    93 

iron  core  is  a  magnet.  Shut  off  the  current 
from  the  battery  and  the  iron  is  still  a  mag- 
net— weak,  true,  but  it  will  always  retain  a 
small  portion  of  its  magnetism.  Soft  iron 
retains  very  little  of  its  magnetism.  Hard 
steel  retains  a  great  deal,  and  for  this  reason 
steel  is  used  for  permanent  magnets,  of  the 
horseshoe  type  so  familiar. 

A  Simple  Dynamo 

A  dynamo  consists,  first,  of  a  number  of 
such  magnets,  wound  with  insulated  wire. 
Their  iron  cores  point  towards  the  center  of  a 
circle  like  the  spokes  of  a  wheel;  and  their 
curved  inner  faces  form  a  circle  in  which  a 
spool,  w^ound  with  wire  in  another  way,  may 
be  spun  by  the  water  wheel. 

Now  take  a  piece  of  copper  wire  and  make 
a  loop  of  it.  Pass  one  side  of  this  loop  in  front 
of  an  electric  magnet. 

As  the  wire  you  hold  in  your  hands  passes 
the  iron  face  of  the  magnet,  a  wave  of  energy 
that  is  called  electricity  flows  around  this  loop 
at  the  rate  of  186,000  miles  a  second — the 


94          ELECTRICITY  FOR  THE  FARM 

same  speed  as  light  comes  to  us  from  the  sun. 
As  you  move  the  wire  away  from  the  magnet, 
a  second  wave  starts  through  the  wire,  flowing 
in  the  opposite  direction.  You  can  prove  this 
by  holding  a  compass  needle  under  the  wire 
and  see  it  wag  first  in  one  direction,  then  in 
another. 


A  wire  "cutting"  the  lines  of  force  of  an  electro-magnet 

This  is  a  simple  dynamo.  A  wire  "cutting" 
the  invisible  lines  of  force,  that  a  magnet  is 
spraying  out  into  the  air,  becomes  "electri- 
fied." Why  this  is  true,  no  one  has  ever  been 
able  to  explain. 

The  amount  of  electricity — its  capacity  for 
work — which  you  have  generated  with  the 
magnet  and  wire,  does  not  depend  alone  on 
the  pulling  power  of  that  simple  magnet.  Let 
us  say  the  magnet  is  very  weak — has  not 
enough  power  to  lift  one  ounce  of  iron.  Never- 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    95 

theless,  if  you  possessed  the  strength  of 
Hercules,  and  could  pass  that  wire  through 
the  field  of  force  of  the  magnet  many  thou- 
sands of  times  a  second,  you  would  generate 
enough  electricity  in  the  wire  to  cause  the 
wire  to  melt  in  your  hands  from  heat. 


\ 

Cross-section  of  an  armature  revolving  in  its  field 

This  experiment  gives  the  theory  of  the 
dynamo.  Instead  of  passing  only  one  wire 
through  the  field  of  force  of  a  magnet,  we  have 
hundreds  bound  lengthwise  on  a  revolving 
drum  called  an  armature.  Instead  of  one 
magnetic  pole  in  a  dynamo  we  have  two,  or 


96          ELECTRICITY  FOR  THE  FARM 

four,  or  twenty  according  to  the  work  the 
machine  is  designed  for — always  in  pairs,  a 
North  pole  next  to  a  South  pole,  so  that  the 
lines  of  force  may  flow  out  of  one  and  into 
another,  instead  of  escaping  in  the  surrounding 
air.  If  you  could  see  these  lines  of  force,  they 
would  appear  in  countless  numbers  issuing 
from  each  pole  face  of  the  field  magnets, 


Forms  of  annealed  steel  discs  used  in  armature  construction 

pressing  against  the  revolving  drum  like  hair 
brush  bristles — trying  to  hold  it  back.  This 
drum,  in  practice,  is  built  up  of  discs  of 
annealed  steel,  and  the  wires  extending  length- 
wise on  its  face  are  held  in  place  by  slots  to 
prevent  them  from  flying  off  when  the  drum 
is  whirled  at  high  speed.  The  drum  does  not 
touch  the  face  of  the  magnets,  but  revolves  in 
an  air  space.  If  we  give  the  electric  impulses 
generated  in  these  wires  a  chance  to  flow  in  a 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    97 

circuit — flow  out  of  one  end  of  the  wires,  and 
in  at  the  other,  the  drum  will  require  more  and 
more  power  to  turn  it,  in  proportion  to  the 
amount  of  electricity  we  permit  to  flow.  Thus, 
if  one  electric  light  is  turned  on,  the  drum  will 
press  back  with  a  certain  strength  on  the 
water  wheel;  if  one  hundred  lights  are  turned 


An  armature  partly  wound,  showing  slots  and  commutator 

on  it  will  press  back  one  hundred  times  as 
much.  Providing  there  is  enough  power  hi 
the  water  wheel  to  continue  turning  the  drum 
at  its  predetermined  speed,  the  dynamo  will 
keep  on  giving  more  and  more  electricity  if 
asked  to,  until  it  finally  destroys  itself  by  fire. 
You  cannot  take  more  power,  in  terms  of  elec- 
tricity, out  of  a  dynamo  that  you  put  into 
it,  in  terms  of  mechanical  motion.  In  fact, 


98  ELECTRICITY  FOR  THE  FARM 

to  insure  flexibility  and  constant  speed  at  all 
loads,  it  is  customary  to  provide  twice  as  much 
water  wheel,  or  engine,  power  as  the  electrical 
rating  of  the  dynamo. 

We  have  seen  that  a  water  wheel  is  85  per 
cent  efficient  under  ideal  conditions.  A 
dynamo's  efficiency  in  translating  mechanical 
motion  into  electricity,  varies  with  the  type 
of  machine  and  its  size.  The  largest  machines 
attain  as  high  as  90  per  cent  efficiency;  the 
smallest  ones  run  as  low  as  40  per  cent. 

Measuring  Electric  Power 

The  amount  of  electricity  any  given  dynamo 
can  generate  depends,  generally  speaking,  on 
two  factors,  i.  e.,  (1)  the  power  of  the  water 
wheel,  or  other  mechanical  engine  that  turns 
the  armature;  and  (2)  the  size  (carrying 
capacity)  of  the  wires  on  this  drum. 

Strength,  of  electricity,  is  measured  in  am- 
peres. An  ampere  of  electricity  is  the  unit 
of  the  rate  of  flow  and  may  be  likened  to  a 
gallon  of  water  per  minute. 

in  surveying  for  water-power,  in  Chapter 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    99 

III,  we  found  that  the  number  of  gallons  or 
cubic  feet  of  water  alone  did  not  determine  the 
amount  of  power.  We  found  that  the  number 
of  gallons  or  cubic  feet  multiplied  by  the 
distance  in  feet  it  falls  in  a  given  time,  was  the 
determining  factor — pounds  (quantity)  multi- 
plied by  feet  per  second — (velocity). 


Showing  the  analogy  of  water  to  volts  and  amperes  of  electricity 

The  same  is  true  in  figuring  the  power  of 
electricity.  We  multiply  the  amperes  by  the 
number  of  electric  impulses  that  are  created 
in  the  wire  in  the  course  of  one  second.  The 
unit  of  velocity,  or  pressure  of  the  electric 
current  is  called  a  volt.  Voltage  is  the  pressure 
which  causes  electricity  to  flow.  A  volt  may 
be  likened  to  the  velocity  in  feet  per  second 
of  water  in  falling  past  a  certain  point.  If  you 


100         ELECTRICITY  FOR  THE  FARM 

think  a  moment  you  will  see  that  this  has 
nothing  to  do  with  quantity.  A  pin-hole 
stream  of  water  under  40  pounds  pressure  has 
the  same  velocity  as  water  coming  from  a 
nozzle  as  big  as  a  barrel,  under  the  same  pres- 
sure. So  with  electricity  under  the  pressure 
of  one  volt  or  one  hundred  volts. 

One  volt  is  said  to  consist  of  a  succession  of 
impulses  caused  by  one  wire  cutting  100,000,000 
lines  of  magnetic  force  in  one  second.  Thus,  if 
the  strength  of  a  magnet  consisted  of  one  line 
of  force,  to  create  the  pressure  of  one  volt 
we  would  have  to  "cut"  that  line  of  force 
100,000,000  times  a  second,  with  one  wire;  or 
100,000  times  a  second  with  one  thousand 
wires.  Or,  if  a  magnet  could  be  made  with 
100,000,000  lines  of  force,  a  single  wire  cutting 
those  lines  once  in  a  second  would  create  one 
volt  pressure.  In  actual  practice,  field  mag- 
nets of  dynamos  are  worked  at  densities  up  to 
and  over  100,000  lines  of  force  to  the  square 
inch,  and  armatures  contain  several  hundred 
conductors  to  "cut"  these  magnetic  lines. 
The  voltage  then  depends  on  the  speed  at 


DYNAMO;  WHAT  IT  DOES,-  £N1>  IStiti  \ 

which  the  armature  is  driven.  In  machines 
for  isolated  plants,  it  will  be  found  that  the 
speed  varies  from  400  revolutions  per  minute, 
to  1,800,  according  to  the  design  of  dynamo 
used. 

Multiplying  amperes  (strength)  by  volts 
(pressure),  gives  us  watts  (power).  Seven 
hundred  and  forty-six  watts  of  electrical 
energy  is  equal  to  one  horsepower  of  me- 
chanical energy — will  do  the  same  work. 
Thus  an  electric  cur- 
rent  under  a  pres- 


sure   of    100   volts,   l-\~4  +-"-4  I*?p4  j.;j} 

and      a      density      of     Pressure  determines  volume  of  flow 

7.46  amperes,  is  one  in  a  *yea  time 

horsepower;  as  is  74.6  amperes,  at  10  volts 
pressure;  or  746  amperes  at  one  volt  pressure. 
For  convenience  (as  a  watt  is  a  small  quantity) 
electricity  is  measured  in  kilowatts,  or  1,000 
watts.  Since  746  watts  is  one  horsepower, 
1,000  watts  or  one  kilowatt  is  1.34  horsepower. 
The  work  of  such  a  current  for  one  hour  is 
called  a  kilowatt-hour,  and  in  our  cities,  where 
electricity  is  generated  from  steam,  the  retail 


ELECTRICITY  FOR  THE  FARM 

price  of  a  kilowatt-hour  varies  from  10  to  15 
cents. 

Now  as  to  how  electricity  may  be  controlled, 
so  that  a  dynamo  will  not  burn  itself  up  when 
it  begins  to  generate. 

Again  we  come  back  to  the  analogy  of  water. 
The  amount  of  wrater  that  passes  through  a 
pipe  in  any  given  time,  depends  on  the  size 
of  the  pipe,  if  the  pressure  is  maintained 
uniform.  In  other  words  the  resistance  of  the 
pipe  to  the  flow  of  water  determines  the 
amount.  If  the  pipe  be  the  size  of  a  pin- 
hole,  a  very  small  amount  of  water  will  escape. 
If  the  pipe  is  as  big  around  as  a  barrel,  a 
large  amount  will  force  its  way  through.  So 
with  electricity.  Resistance,  introduced  in  the 
electric  circuit,  controls  the  amount  of  current 
that  flows.  A  wire  as  fine  as  a  hair  will  permit 
only  a  small  quantity  to  pass,  under  a  given 
pressure.  A  wire  as  big  as  one's  thumb  will 
permit  a  correspondingly  greater  quantity  to 
pass,  the  pressure  remaining  the  same.  The 
unit  of  electrical  resistance  is  called  the  ohm — 
named  after  a  man,  as  are  all  electrical  units. 


DYNAMO;  WHAT  IT  DOES,  AND  HOW     103 

Ohms  Law 

The  ohm  is  that  amount  of  resistance  that 
will  permit  the  passage  of  one  ampere,  under 
the  pressure  of  one  volt.  It  would  take  two 
volts  to  force  two  amperes  through  one  ohm; 
or  100  volts  to  force  100  amperes  through  the 
resistance  of  one  ohm.  From  this  we  have 
Ohm's  Law,  a  simple  formula  which  is  the 
beginning  and  end  of  all  electric  computations 
the  farmer  will  have  to  make  in  installing  his 
water-power  electric  plant.  Ohm's  Law  tells 
us  that  the  density  of  current  (amperes) 
that  can  pass  through  a  given  resistance  in 
ohms  (a  wire,  a  lamp,  or  an  electric  stove) 
equals  volts  divided  by  ohms — or  pressure 
divided  by  resistance.  This  formula  may  be 
written  in  three  ways,  thus : 

C  =  |,  or  R  =  §  or,  E  =  C  x  R.  Or  to  ex- 
press the  same  thing  in  words,  current  equals 
volts  divided  by  ohms;  ohms  equals  volts  divided 
by  current;  or  volts  equals  current  multiplied  by 
ohms.  So,  with  any  two  of  these  three  deter- 
mining factors  known,  we  can  find  the  third. 


104         ELECTRICITY  FOR  THE  FARM 

As  we  have  said,  this  simple  law  is  the  begin- 
ning and  end  of  ordinary  calculations  as  to 
electric  current,  and  it  should  be  thoroughly 
understood  by  any  farmer  who  essays  to  be 
his  own  electrical  engineer.  Once  understood 
and  applied,  the  problem  of  the  control  of  the 
electric  current  becomes  simple  a  b  c. 

Examples  of  Ohm's  Law 

Let  us  illustrate  its  application  by  an 
example.  The  water  wheel  is  started  and  is 
spinning  the  dynamo  at  its  rated  speed,  say 
1,500  r.  p.  m.  Two  heavy  wires,  leading  from 
brushes  which  collect  electricity  from  the 
revolving  armature,  are  led,  by  suitable  in- 
sulated supports  to  the  switchboard,  and 
fastened  there.  They  do  not  touch  each  other. 
Dynamo  mains  must  not  be  permitted  to 
touch  each  other  under  any  conditions.  They 
are  separated  by  say  four  inches  of  air.  Dry 
air  is  a  very  poor  conductor  of  electricity.  Let 
us  say,  for  the  example,  that  dry  air  has  a 
resistance  to  the  flow  of  an  electric  current,  of 
1,000,000  ohms  to  the  inch— that  would  be 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    105 

4,000,000  ohms.  How  much  electricity  is 
being  permitted  to  escape  from  the  armature 
of  this  110-volt  dynamo,  when  the  mains  are 
separated  by  four  inches  of  dry  air?  Apply 
Ohm's  law,  C  equals  E  divided  by  R.  E,  in 
this  case  is  110;  R  is  4,000,000;  therefore  C 
(amperes)  equals  110/4,000,000 — an  infinites- 
imal amount — about  .0000277  ampere. 

Let  us  say  that  instead  of  separating  these 
two  mains  by  air  we  separated  them  by  the 
human  body — that  a  man  took  hold  of  the 
bare  wires,  one  in  each  hand.  The  resistance 
of  the  human  body  varies  from  5,000  to 
10,000  ohms.  In  that  case  C  (amperes) 
equals  110/5,000,  or  110/10,000— about  l/50th, 
or  1/1 00th  of  an  ampere.  This  illustrates 
why  an  electric  current  of  110  volts  pres- 
sure is  not  fatal  to  human  beings,  under 
ordinary  circumstances.  The  body  offers 
too  much  resistance.  But,  if  the  volts  were 
1,100  instead  of  the  usual  110  used  in  com- 
mercial and  private  plants  for  domestic  use, 
the  value  of  C,  by  this  formula  at  5,000  ohms, 
would  be  nearly  1/5 th  ampere.  To  drive  l/5th 


106         ELECTRICITY  FOR  THE  FARM 

ampere  of  electricity  through  the  human  body 
would  be  fatal  in  many  instances.  The  higher 
the  voltage,  the  more  dangerous  the  current. 
In  large  water-power  installations  in  the  Far 
West,  where  the  current  must  be  transmitted 
over  long  distances  to  the  spot  where  it  is  to 
be  used,  it  is  occasionally  generated  at  a  pres- 
sure of  150,000  volts.  Needless  to  say,  contact 
with  such  wires  means  instant  death.  Before 
being  used  for  commercial  or  domestic  pur- 
poses, in  such  cases,  the  voltage  is  "stepped 
down"  to  safe  pressures — to  110,  or  to  220, 
or  to  550  volts — always  depending  on  the  use 
made  of  it. 

Now,  if  instead  of  interposing  four  inches 
of  air,  or  the  human  body,  between  the  mains 
of  our  110- volt  dynamo,  we  connected  an 
incandescent  lamp  across  the  mains,  how 
much  electricity  would  flow  from  the  gen- 
erator? An  incandescent  lamp  consists  of  a 
vacuum  bulb  of  glass,  in  which  is  mounted 
a  slender  thread  of  carbonized  fibre,  or  fine 
tungsten  wire.  To  complete  a  circuit,  the 
current  must  flow  through  this  wire  or  fila- 


DYNAMO;  WHAT  IT  DOES,  AND  HOW     107 

ment.  In  flowing  through  it,  the  electric 
current  turns  the  wire  or  filament  white  hot — 
incandescent — and  thus  turns  electricity  back 
into  light,  with  a  small  loss  in  heat.  In  an 
ordinary  16  candlepower  carbon  lamp,  the 
resistance  of  this  filament  is  220  ohms.  There- 
fore the  amount  of  current  that  a  110-volt 
generator  can  force  through  that  filament  is 
or  }/£  ampere. 


Armature  and  field  coils  of  a  direct  current  dynamo 

One  hundred  lamps  would  provide  100 
paths  of  220  ohms  resistance  each  to  carry 
current,  and  the  amount  required  to  light 
100  such  lamps  would  be  100  x  ^  or  50 
amperes.  Every  electrical  device — a  lamp, 


108         ELECTRICITY  FOR  THE  FARM 

a  stove,  an  iron,  a  motor,  etc., — must,  by 
regulations  of  the  Fire  Underwriters'  Board 
be  plainly  marked  with  the  voltage  of  the 
current  for  which  it  is  designed  and  the  amount 
of  current  it  will  consume.  This  is  usually 
done  by  indicating  its  capacity  in  watts, 
which  as  we  have  seen,  means  volts  times 
amperes,  and  from  this  one  can  figure  ohms, 
by  the  above  formulas. 

A  Short  Circuit 

We  said  a  few  paragraphs  back  that  under 
no  conditions  must  two  bare  wires  leading 
from  electric  mains  be  permitted  to  touch 
each  other,  without  some  form  of  resistance 
being  interposed  in  the  form  of  lamps,  or 
other  devices.  Let  us  see  what  would  happen 
if  two  such  bare  wires  did  touch  each  other. 
Our  dynamo  as  we  discover  by  reading  its 
plate,  is  rated  to  deliver  50  amperes,  let  us 
say,  at  110  volts  pressure.  Modern  dynamos 
are  rated  liberally,  and  can  stand  100% 
overload  for  short  periods  of  time,  without 
dangerous  overheating.  Let  us  say  that  the 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    109 

mains  conveying  current  from  the  armature 
to  the  switchboard  are  five  feet  long,  and  of 
No.  2  B.  &  S.  gauge  copper  wire,  a  size  which 
will  carry  50  amperes  without  heating  appre- 
ciably. The  resistance  of  this  10  feet  of  No.  2 
copper  wire,  is,  as  we  find  by  consulting  a 
wire  table,  .001560  ohms.  If  we  touch  the 
ends  of  these  two  five-foot  wires  together, 
we  instantly  open  a  clear  path  for  the  flow  of 
electric  current,  limited  only  by  the  carrying 
capacity  of  the  wire  and  the  back  pressure 
of  .001560  ohms  resistance.  Using  Ohm's 
Law,  C  equals  E  divided  by  R,  we  find  that  C 
(amperes)  equals  .WiVW  or  70,515  amperes! 

Unless  this  dynamo 
were  properly  pro- 
tected, the  effect  of 
such  a  catastrophe 
would  be  immediate 
and  probably  irrepara- 
ble. In  effect,  it  Would  A  direct  current  dynamo 

be  suddenly  exerting  a  force  of  nearly 
10,000  horsepower  against  the  little  10  horse- 
power water  wheel  that  is  driving  this 


110         ELECTRICITY  FOR  THE  FARM 

dynamo.  The  mildest  thing  that  could  hap- 
pen would  be  to  melt  the  feed-wire  or  to 
snap  the  driving  belt,  in  which  latter  case  the 
dynamo  would  come  to  a  stop.  If  by  any 
chance  the  little  water  wheel  was  given  a 
chance  to  maintain  itself  against  the  blow 
for  an  instant,  the  dynamo,  rated  at  50  am- 
peres, would  do  its  best  to  deliver  the  70,515 
amperes  you  called  for — and  the  result  would 
be  a  puff  of  smoke,  and  a  ruined  dynamo. 
This  is  called  a  "short  circuit"— one  of  the 
first  "don'ts"  in  handling  electricity. 

As  a  matter  of  fact  every  dynamo  is  pro- 
tected against  such  a  calamity  by  means  of 
safety  devices,  which  will  be  described  in  a 
later  chapter — because  no  matter  how  care- 
ful a  person  may  be,  a  partial  short  circuit 
is  apt  to  occur.  Happily,  guarding  against  its 
disastrous  effects  is  one  of  the  simplest  prob- 
lems in  connection  with  the  electric  plant. 

Direct  Current  and  Alternating  Current 

When  one  has  mastered  the  simple  Ohm's 
Law  of  the  electric  circuit,  the  next  step  is  to 


DYNAMO;  WHAT  IT  DOES,  AND  HOW     111 

determine  what  type  of  electrical  generator 
is  best  suited  to  the  requirements  of  a  farm 
plant. 

In  the  first  place,  electric  current  is  divided 
into  two  classes  of  interest  here — alternating, 
and  direct. 

We  have  seen  that  when  a  wire  is  moved 
through  the  field  of  a  magnet,  there  is  induced 
in  it  two  pulsations — first  in  one  direction, 
then  in  another.  This  is  an  alternating  cur- 
rent, so  called  because  it  changes  its  direction. 
If,  with  our  armature  containing  hundreds 
of  wires  to  "cut"  the  lines  of  force  of  a  group 
of  magnets,  we  connected  the  beginning  of 
each  wire  with  one  copper  ring,  and  the  end 
of  each  wire  with  another  copper  ring,  we 
would  have  what  is  called  an  alternating- 
current  dynamo.  Simply  by  pressing  a  strap 
of  flexible  copper  against  each  revolving  copper 
ring,  we  would  gather  the  sum  of  the  current 
of  these  conductors.  Its  course  would  be 
represented  by  the  curved  line  in  the  diagram, 
one  loop  on  each  side  of  the  middle  line  (which 
represents  time)  would  be  a  cycle.  The  num- 


112         ELECTRICITY  FOR  THE  FARM 

her  of  cycles  to  the  second  depends  on  the 
speed  of  the  armature;  in  ordinary  practice 
it  is  usually  twenty-five  or  sixty.  Alternat- 
ing current  has  many  advantages,  which 
however,  do  not  concern  us  here.  Except 
under  very  rare  conditions,  a  farmer  installing 
his  own  plant  should  not  use  this  type  of 
machine. 


WAVE  REFGEaENTING  BACK-AND-FCKTH  FLOW  OF  ALTERNATING  CV&R£NT 


LOfE  R£PI3£S£tfTlIfG  FLOW  OF   DIRECT 

Diagram  of  alternating  and  direct  current 

If,  however,  instead  of  gathering  all  the 
current  with  brushes  bearing  on  two  copper 
rings,  we  collected  all  the  current  traveling 
in  one  direction,  on  one  set  of  brushes  — 
and  all  the  current  traveling  in  the  other  di- 
rection on  another  set  of  brushes,  —  we  would 
straighten  out  this  current,  make  it  all  travel 
in  one  dire^ion.  Then  we  would  have  a 
direct  current.  A  direct  current  dynamo,  the 
type  generally  used  in  private  plants,  does 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    113 

this.  Instead  of  having  two  copper  rings 
for  collecting  the  current,  it  has  a  single  ring, 
made  up  of  segments  of  copper  bound  together, 
but  insulated  from  each  other,  one  segment  for 
each  set  of  conductors  on  the  armature.  This 
ring  of  many  segments,  is  called  a  commuta- 
tor, because  it  commutates,  or  changes,  the 
direction  of  the  electric  impulses,  and  delivers 
them  all  in  one  direction.  In  effect,  it  is 
like  the  connecting  rod  of  a  steam  engine  that 
straightens  out  the  back-and-forth  motion 
of  the  piston  in  the  steam  cylinder  and  delivers 
the  motion  to  a  wheel  running  in  one  direction. 
Such  a  current,  flowing  through  a  coil  of 
wire  would  make  a  magnet,  one  end  of  which 
would  always  be  the  north  end,  and  the 
other  end  the  south  end.  An  alternating  cur- 
rent, on  the  other  hand,  flowing  through  a 
coil  of  wire,  would  make  a  magnet  that 
changed  its  poles  with  each  half-cycle.  It 
would  no  sooner  begin  to  pull  another  mag- 
net to  it,  than  it  would  change  about  and 
push  the  other  magnet  away  from  it,  and 
so  on,  as  long  as  it  continued  to  flow.  This 


114         ELECTRICITY  FOR  THE  FARM 

is  one  reason  why  a  direct  current  dynamo 
is  used  for  small  plants.  Alternating  current 
will  light  the  same  lamps  and  heat  the  same 
irons  as  a  direct  current;  but  for  electric 
power  it  requires  a  different  type  of  motor. 

Types  of  Direct  Current  Dynamos 

Just  as  electrical  generators  are  divided 
into  two  classes,  alternating  and  direct,  so  j 
direct  current  machines  are  divided  into 
three  classes,  according  to  the  manner  in  which 
their  output,  in  amperes  and  volts,  is  regulated. 
They  differ  as  to  the  manner  in  which  their 
field  magnets  (in  whose  field  of  force  the 
armature  spins)  are  excited,  or  made  mag- 
netic. They  are  called  series,  shunt,  and 
compound  machines. 

The  Series  Dynamo 

By  referring  to  the  diagram,  it  will  be  seen  j 
that  the  current  of  a  series  dynamo  issues  from 
the  armature  mains,  and  passes  through  the 
coils  of  the  field  magnets  before  passing  into 
the  external   circuit   to   do   its   work.     The 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    115 

residual  magnetism,  or  the  magnetism  left 
in  the  iron  cores  of  the  field  magnets  from  its 
last  charge,  provides  the  initial  excitation, 
when  the  machine  is  started.  As  the  resis- 
tance of  the  external  circuit  is  lowered,  by 
turning  on  more  and  more  lights,  more  and 
more  current  flows  from  the  armature,  through 
the  field  magnets.  Each  time  the  resistance 
is  lowered,  therefore,  the  current  passing 
through  the  field  magnets  becomes  more  dense 
in  amperes,  and  makes  the  field  magnets 
correspondingly  stronger. 

We  have  seen  that  the  voltage  depends  on 
the  number  of  lines  of  magnetic  force  cut  by 
the  armature  conductors  in  a  given  time.  If 
the  speed  remains  constant  then,  and  the 
magnets  grow  stronger  and  stronger,  the  volt- 
age will  rise  in  a  straight  line.  When  no  cur- 
rent is  drawn,  it  is  0;  at  full  load,  it  may  be 
100  volts,  or  500,  or  1,000  according  to  the 
machine.  This  type  of  machine  is  used  only 
in  street  lighting,  in  cities,  with  the  lights 
connected  in  "series,"  or  one  after  another  on 
the  same  wire,  the  last  lamp  finally  returning 


116        ELECTRICITY  FOR  THE  FARM 

the  wire  to  the  machine  to  complete  the  cir- 
cuit.    This  type  of  dynamo  has  gained  the 

name  f°r  itself  of 
"mankiller,"  as  its 
voltage  becomes  enor- 
mous at  full  load.  It 
is  unsuitable,  in  every 
respect,  for  the  farm 
plant.  Its  field  coils 

Connections  of  a  series  dynamo       consist  of  a  f CW  turns 

of  very  heavy  wire,  enough  to  carry  all  the  cur- 
rent of  the  external  circuit,  without  heating. 

The  Shunt  Dynamo 

The  shunt  dynamo,  on  the  other  hand,  has 
field  coils  connected  directly  across  the  cir- 
cuit, from  one  wire  to  another,  instead  of  in 
"series."  These  coils  consist  of  a  great 
many  turns  of  very  fine  wire,  thus  introducing 
resistance  into  the  circuit,  which  limits  the 
amount  of  current  (amperes)  that  can  be 
forced  through  them  at  any  given  voltage. 
As  a  shunt  dynamo  is  brought  up  to  its  rated 
speed,  its  voltage  gradually  rises  until  a  con- 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    117 


dition  of  balance  occurs  between  the  field 
coils  and  the  armature.  There  it  remains  con- 
stant. When  re- 

I  ToLoad 

sistance  on  the  ex-  * 

ternal  circuit  is 
lowered,  by  means 
of  turning  on 
lamps  or  other  de- 
vices, the  current 
from  the  armature 
increases  in  work- 


Connections  of  a  shunt  dynamo 


ing  power,  by  increasing  its  amperes.  Its 
voltage  remains  stationary;  and,  since  the 
resistance  of  its  field  coils  never  changes,  the 
magnets  do  not  vary  in  strength. 

The  objection  to  this  type  of  machine  for  a 
farm  plant  is  that,  in  practice,  the  armature 
begins  to  exercise  a  de-magnetizing  effect  on 
the  field  magnets  after  a  certain  point  is 
reached — weakens  them;  consequently  the 
voltage  begins  to  fall.  The  voltage  of  a 
shunt  dynamo  begins  to  fall  after  half -load  is 
reached;  and  at  full  load,  it  has  fallen  pos- 
sibly 20  per  cent.  A  rheostat,  or  resistance 


118        ELECTRICITY  FOR  THE  FARM 

box  on  the  switchboard,  makes  it  possible 
to  cut  out  or  switch  in  additional  resistance 
in  the  field  coils,  thus  varying  the  strength 
of  the  field  coils,  within  a  limit  of  say  15 
per  cent,  to  keep  the  voltage  constant.  This, 
however,  requires  a  constant  attendance  on 
the  machine.  If  the  voltage  were  set  right 
for  10  lights,  the  lights  would  grow  dim  when 
50  lights  were  turned  on;  and  if  it  were  ad- 
justed for  50  lights,  the  voltage  would  be  too 
high  for  only  ten  lights — would  cause  them  to 
"burn  out." 

Shunt  dynamos  are  used  for  charging 
storage  batteries,  and  are  satisfactory  for 
direct  service  only  when  an  attendant  is 
constantly  at  hand  to  regulate  them. 

The  Compound  Dynamo 

The  ideal  between  these  two  conditions 
would  be  a  compromise,  which  included  the 
characteristics  of  both  series  and  shunt  effects. 
That  is  exactly  what  the  compound  dynamo 
effects. 

A  compound  dynamo  is  a  shunt  dynamo 


DYNAMO;  WHAT  IT  DOES,  AND  HOW    119 

with  just  enough  series  turns  on  its  field  coils, 
to  counteract  the  de-magnetizing  effect  of  the 
armature  at  full  load.  A  machine  can  be 
designed  to  make  the  voltage  rise  gradually, 
or  swiftly,  by  combining  the  two  systems. 
For  country  homes,  the  best  combination  is  a 
machine  that  will  keep  the  voltage  constant 
from  no  load  to  full  load.  A  so-called  flat- 
compounded  machine  does  this.  In  actual 
practice,  this  voltage  rises  slightly  at  the  half- 
load  line — only  two  or  three  volts,  which  will 
not  damage  the  lamps  in  a  110- volt  circuit. 

The  compound  dynamo  is  therefore  self- 
regulating,  and  requires  no  attention,  except 
as  to  lubrication,  and  the  incidental  care 
given  to  any  piece  of  machinery.  Any  shunt 
dynamo  can  be  made  into  a  compound  dy- 
namo, by  winding  a  few  turns  of  heavy  in- 
sulated wire  around  the  shunt  coils,  and  con- 
necting them  in  "series"  with  the  external 
circuit.  How  many  turns  are  necessary  de- 
pends on  conditions.  Three  or  four  turns  to 
each  coil  usually  are  sufficient  for  "flat  com- 
pounding." If  the  generating  plant  is  a  long 


120         ELECTRICITY  FOR  THE  FARM 


distance  from  the  farm  house  where  the  light, 
heat,  and  power  are  to  be  used,  the  voltage 
drops  at  full  load,  due  to  resistance  of  the  trans- 
mission wires.  To  overcome  this,  enough 
turns  can  be  wound  on  top  of  the  shunt  coils 

to  cause  the  volt- 
age to  rise  at  the 
switchboard,  but 
remain  stationary 

at  tne  sPot  where 
the  current  is  used. 
The  usual  so-called 
flat -compounded 

Connections  of  a  compound  dynamo      dynamo,         turned 

out  by  manufacturers,  provides  for  constant 
voltage  at  the  switchboard.  Such  a  dynamo 
is  eminently  fitted  for  the  farm  electric  plant. 
Any  other  type  of  machine  is  bound  to  cause 
constant  trouble  and  annoyance. 


CHAPTER  VI 

WHAT    SIZE   PLANT   TO   INSTALL 

The  farmer's  wife  his  partner — Little  and  big  plants — 
Limiting  factors — Fluctuations  in  water  supply — 
The  average  plant — The  actual  plant — Amount 
of  current  required  for  various  operations — Stand- 
ard voltage — A  specimen  allowance  for  electric 
light — Heating  and  cooking  by  electricity — Elec- 
tric power:  the  electric  motor. 

THE  farmer's  wife  becomes  his  partner  when 
he  has  concluded  the  preliminary  measure- 
ments and  surveys  for  building  his  water- 
power  electric  plant.  Now  the  question  is, 
how  big  a  plant  is  necessary,  or  how  small  a 
plant  can  he  get  along  with.  Electricity  may 
be  used  for  a  multitude  of  purposes  on  the 
farm,  in  its  sphere  of  furnishing  portable  light, 
heat  and  power;  but  when  this  multitude  of 
uses  has  been  enumerated,  it  will  be  found  that 
the  wife  shares  in  the  benefits  no  less  than  the 

farmer  himself.    The  greatest  dividend  of  all, 

121 


ELECTRICITY  FOR  THE  FARM 

whether  dividends  are  counted  in  dollars  or 
happiness,  is  that  electricity  takes  the  drudg- 
ery out  of  housework.  Here,  the  work  of  the 
farmer  himself  ends  when  he  has  brought 
electricity  to  the  house,  just  as  his  share  in 
housework  ends  when  he  has  brought  in  the 
kerosene,  and  filled  the  woodbox.  Of  the 
light  and  heat,  she  will  use  the  lion's  share; 
and  for  the  power,  she  will  discover  heretofore 
undreamed-of  uses.  So  she  must  be  a  full 
partner  when  it  comes  to  deciding  how  much 
electricity  they  need. 

How  much  electricity,  in  terms  of  light, 
heat,  and  power,  will  the  farmer  and  his  wife 
have  use  for?  How  big  a  plant  should  be 
installed  to  meet  the  needs  of  keeping  house 
and  running  the  farm? 

The  answer  hangs  mainly  on  how  much 
water-power  there  is  available,  through  all  the 
seasons  of  the  year,  with  which  to  generate 
electricity.  Beyond  that,  it  is  merely  a  ques- 
tion of  the  farmer's  pocketbook.  How  much 
money  does  he  care  to  spend?  Electricity 
is  a  cumulative  "poison."  The  more  one  uses 


WHAT  SIZE  PLANT  TO  INSTALL        123 

it,  the  more  he  wants  to  use  it.  After  a  plant 
has  been  in  operation  a  year,  the  family  have 
discovered  uses  for  electricity  which  they  did 
not  think  of  in  the  beginning.  For  this  reason, 
it  is  well  to  put  in  a  plant  larger  than  the  needs 
of  the  moment  seem  to  require.  An  electrical 
horsepower  or  two  one  way  or  another  will 
not  greatly  change  the  first  cost,  and  you  will 
always  find  use  for  any  excess. 

Once  for  all,  to  settle  the  question  of  water- 
power,  the  water  wheel  should  be  twice  the 
normal  capacity  of  the  dynamo  it  drives,  in 
terms  of  power.  This  allows  for  overload, 
which  is  bound  to  occur  occasionally;  and  it 
also  insures  smooth  running,  easy  governing, 
and  the  highest  efficiency.  Since  the  electric 
current,  once  the  plant  is  installed,  will  cost 
practically  nothing,  the  farmer  can  afford  to 
ignore  the  power  going  to  waste,  and  consider 
only  how  to  get  the  best  service. 

The  Two  Extremes 

The  amount  of  water  to  be  had  to  be  turned 
into  electricity,  will  vary  with  location,  and 


124         ELECTRICITY  FOR  THE  FARM 

with  the  season.  It  may  be  only  enough,  the 
greater  part  of  the  year,  for  a  "toy"  plant — a 
very  practical  toy,  by  the  way — one  that  will 
keep  half  a  dozen  lights  burning  in  the  house 
and  barn  at  one  time;  under  some  conditions 
water  may  be  so  scarce  that  it  must  be  stored 
for  three  or  four  days  to  get  enough  power  to 
charge  a  storage  battery  for  these  six  or  eight 
lights.  A  one-quarter,  or  a  one-half  kilowatt 
electrical  generator,  with  a  one  horsepower 
(or  smaller)  wheel,  will  light  a  farmstead  very 
satisfactorily — much  better  than  kerosene 
lamps. 

On  the  other  hand,  the  driving  power  of 
your  wheel  may  be  sufficient  to  furnish  50  or 
100  lights  for  the  house,  barn,  and  out-build- 
ings, and  barn-yard  and  drives;  to  provide 
ample  current  for  irons,  toasters,  vacuum 
cleaners,  electric  fans,  etc. ;  to  do  all  the  cook- 
ing and  baking  and  keep  the  kitchen  boiler 
hot;  and  to  heat  the  house  in  the  coldest 
weather  with  a  dry  clean  heat  that  does  not 
vitiate  the  air,  with  no  ashes,  smoke  or  dust  or 
woodchopping — nothing  but  an  electric  switch 


WHAT  SIZE  PLANT  TO  INSTALL        125 

to  turn  on  and  off;  and  to  provide  power  for 
motors  ranging  from  tiny  ones  to  run  the 
sewing  machine,  to  one  of  15  horsepower  to  do 
the  threshing.  A  plant  capable  of  developing 
from  30  to  50  kilowatts  of  electricity,  and  re- 
quiring from  50  to  100  horsepower  at  the 
water  wheel,  would  do  all  this,  depending  on 
the  size  of  the  farmstead.  One  hundred  horse- 
power is  a  very  small  water  project,  in  a  com- 
mercial way;  and  there  are  thousands  of  farms 
possessing  streams  of  this  capacity. 

Fluctuations  in  Water  Supply 

It  would  be  only  during  the  winter  months 
that  such  a  plant  would  be  driven  to  its  full 
capacity;  and  since  water  is  normally  plentiful 
during  these  months,  the  problem  of  power 
would  be  greatly  simplified.  The  heaviest 
draft  on  such  a  plant  in  summer  would  be 
during  harvesting;  otherwise  it  would  be  con- 
fined to  light,  small  power  for  routine  work, 
and  cooking.  Thus,  a  plant  capable  of  meet- 
ing all  the  ordinary  requirements  of  the  four 
dry  months  of  summer,  when  water  is  apt  to 


126        ELECTRICITY  FOR  THE  FARM 

be  scarce,  doubles  or  quadruples  its  capacity 
during  the  winter  months,  to  meet  the  neces- 
sities of  heat  for  the  house. 

A  dynamo  requires  only  as  much  power  to 
drive  it,  at  any  given  time,  as  is  being  used  in 
terms  of  electricity.  There  is  some  small 
loss  through  friction,  of  course,  but  aside  from 
this  the  power  required  of  the  prime  mover 
(the  water  wheel)  is  always  in  proportion  to 
the  amount  of  current  flowing.  When  water 
is  scarce,  and  the  demands  for  current  for 
heating  are  low,  it  is  good  practice  to  close  a 
portion  of  the  buckets  of  the  turbine  wheel 
with  wooden  blocks  provided  for  this  purpose. 
It  is  necessary  to  keep  the  speed  of  the  dynamo 
uniform  under  all  water  conditions;  and  where 
there  is  a  great  fluctuation  between  high  and 
low  water  periods,  it  is  frequently  necessary 
to  have  a  separate  set  of  pulleys  for  full  gate 
and  for  half -gate.  The  head  must  remain  the 
same,  under  all  conditions.  Changing  the 
gate  is  in  effect  choking  or  opening  the  nozzle 
supplying  the  wheel,  to  cut  down  or  increase 
its  consumption  of  water. 


WHAT  SIZE  PLANT  TO  INSTALL       127 

The  Average  Plant 

It  will  be  the  exceptional  plant,  however, 
among  the  hundreds  of  thousands  to  be  had 
on  our  farms,  which  will  banish  not  only  the 
oil  lamp  and  kitchen  stove,  but  all  coal  or 
wood  burning  stoves  as  well — which  will  heat 
the  house  in  below-zero  weather,  and  provide 
power  for  the  heavier  operations  of  the  farm. 
Also,  on  the  other  hand,  it  will  be  the  excep- 
tional plant  whose  capacity  is  limited  to 
furnishing  a  half-dozen  lights  and  no  more. 

A  happy  medium  between  these  two  con- 
ditions is  the  plant  large  enough  to  supply 
between  five  and  ten  electrical  horsepower,  in 
all  seasons.  Such  a  plant  will  meet  the  needs 
of  the  average  farm,  outside  of  winter  heating 
and  large  power  operations,  and  will  provide 
an  excess  on  which  to  draw  in  emergencies,  or 
to  pass  round  to  one's  neighbors.  It  is  such  a 
plant  that  we  refer  to  when  we  say  that  (not 
counting  labor)  its  cost,  under  ordinary  condi- 
tions should  not  greatly  exceed  the  price  of 
one  sound  young  horse  for  farm  work. 


128         ELECTRICITY  FOR  THE  FARM 

Since  the  plant  we  described  briefly  in  the 
first  chapter,  meets  the  requirements  of  this 
"average  plant"  let  us  inquire  a  little  more 
fully  into  its  installation,  maintenance,  and 
cost. 

An  Actual  Plant 

In  this  instance,  the  water-power  was  al- 
ready installed,  running  to  waste,  in  fact.  The 
wheel  consists  of  the  so-called  thirty-six  inch 
vertical  turbine,  using  185  square  inches  of 
water,  under  a  14-foot  head.  Water  is  sup- 
plied to  this  wheel  by  a  wooden  penstock 
33  inches  square,  inside  measurements,  and 
sloping  at  an  angle  of  30°  from  the  flume  to  the 
wheel. 

This  wheel,  under  a  14-foot  head,  takes 
2,312  cubic  feet  of  water  a  minute;  and  it 
develops  46.98  actual  horsepower  (as  may  be 
figured  by  using  the  formulas  of  Chapter  III). 
The  water  supply  is  provided  by  a  small 
mountain  river.  The  dam  is  10  feet  high,  and 
the  race,  which  feeds  the  flume  from  the  mill 
pond  is  75  yards  long.  The  race  has  two 


Details  of  voltmeter  or  ammeter 


WHAT  SIZE  PLANT  TO  INSTALL        129 

spillways,  one  near  the  dam,  and  the  second  at 
the  flume  itself,  to  maintain  an  even  head  of 
water  at  all  times. 

Half-Gate 

Since  the  water  supply  varies  with  the 
seasons,  it  has  been  found  practical  to  run  the 
wheel  at  half -gate — that  is,  with  the  gate  only 
half -open.  A  set  of  bevel  gears  work  the  main 
shaft,  which  runs  at  approximately  200  revolu- 
tions per  minute;  and  the  dynamo  is  worked 
up  to  its  required  speed  of  1,500  revolutions 
per  minute  through  a  countershaft. 

The  dynamo  is  a  modern  four-pole  machine, 
compound-wound,  with  a  rated  output  of 
46  amperes,  at  125  volts — in  other  words  a 
dynamo  of  5.75  kilowatts  capacity,  or  7.7 
electrical  horsepower.  At  full  load  this  dy- 
namo would  require  a  driving  power  of  10 
horsepower,  counting  it  as  75  per  cent  efficient; 
and,  to  conform  to  our  rule  of  two  water 
horsepower  to  one  electrical  horsepower,  the 
wheel  should  be  capable  of  developing  20 
horsepower.  As  a  matter  of  fact,  in  this 


130        ELECTRICITY  FOR  THE  FARM 

particular  instance,  shutting  down  the  wheel 
to  half -gate  more  than  halves  the  rated  power 
of  the  wheel,  and  little  more  than  15  horse- 
power is  available.  This  allowance  has  proved 
ample,  under  all  conditions  met  with,  in  this 
plant. 

The  dynamo  is  mounted  on  a  firm  floor 
foundation;  and  it  is  belted  from  the  counter- 
shaft by  an  endless  belt  running  diagonally. 
A  horizontal  belt  drive  is  the  best.  Vertical 
drive  should  be  avoided  wherever  possible. 

The  Switchboard 

The  switchboard  originally  consisted  of  a 
wooden  frame  on  which  were  screwed  ordinary 
asbestos  shingles,  and  the  instruments  were 
mounted  on  these.  Later,  a  sheet  of  electric 
insulating  fibre  was  substituted,  for  look's  sake. 
The  main  requisite  is  something  substantial — 
and  fireproof.  The  switchboard  instruments 
consist  of  a  voltmeter,  with  a  range  of  from 
0  to  150  volts;  an  ammeter,  with  a  range,  0  to 
75  amperes;  a  field  regulating  rheostat  (which 
came  with  the  dynamo);  a  main  switch,  with 


WHAT  SIZE  PLANT  TO  INSTALL        131 


cartridge  fuses  protecting  the 
machine  against  a  draft  of 
current  over  60  amperes;  and 
two  line  switches  for  the  two 
owners,  one  fuse  at  20  am- 
peres, and  the  other  at  40 
amperes.  Electric  fuses  are 
either  cartridges  or  plugs,  en- 
closing lead  wire  of  a  size 
corresponding  to  their  rating. 
All  the  current  of  the  line 
they  protect  passes  through 
this  lead  wire.  If  the  current 
drawn  exceeds  the  capacity 
of  the  lead  wire,  it  melts 
from  the  heat,  and  thus 
opens  the  circuit,  and  cuts 
off  the  current. 


Items  of  Cost 

This  water  wheel  would 
cost  $250  new.  There  is  a 
duplicate  in  the  neighbor- 
hood bought  at  second-hand,  for  $125.  The 


A  switchboard  and  its 
connections:  G.  Dyna- 
mo; A.  Shunt  field 
coils;  B.  Series  coils; 
DD.  Fuses;  FF.  Main 
switch;  F.  Field  switch; 
C.  Ammeter;  V.  Volt- 
meter; E.  Lamp;  R. 
Rheostat.  Dotted  lines 
show  connections  on 
back  of  board 


132         ELECTRICITY  FOR  THE  FARM 


dynamo  cost  $90,  and  was  picked  up  second- 
hand in  New  York  City.  New  it  would  cost 
$150.  The  voltmeter  cost  $7,  and  the  ammeter 
$10;  and  the  switches  and  fuses  could  be  had 
for  $5.  A  wheel  one-half  the  size,  using  one- 
half  the  amount  of  water  at  full  gate,  would 
do  the  work  required,  and  the  cost  would  be 
correspondingly  less. 

Capacity 

This  plant  supplies  two  farms  with  electric 

light.    One  farm  (that  of  the  owner  of  the  wheel) 

has  30  lamps,  of  16 
candlepower  each,  and 
two  barn-yard  lamps 
of  92  candlepower  each. 
His  wife  has  an  electric 
iron  and  an  electric 
water  heater.  Needless 
to  say,  all  these  lamps, 

and  the  iron  and  water  heater  are  not  in  use 

at  one  time. 

The  partner  who  owns  the  electric  part  of 

the  plant  has  30  lamps  in  his  house  and  barn, 


Carbon  Lamps 
Gem  Type  (%  scale) 


WHAT  SIZE  PLANT  TO  INSTALL       133 

many  of  them  being  25  watt  tungsten,  which 
give  more  light  for  less  power,  but  cost  more 
to  buy.  They  are  not  all  in  use  at  one  time, 
though  (since  the  current  costs  nothing)  the 
inclination  is  to  turn  them  on  at  night  and  let 
them  burn.  In  his  kitchen  he  has  an  electric 
range,  and  a  water  heater  for  the  40  gallon 
boiler.  In  addition  to  this  he  has  all  sorts  of 
appliances, — irons,  toasters,  grills,  a  vacuum 
cleaner,  a  vibrator,  etc.  Naturally  all  these 
appliances  are  not  in  use  at  one  time,  else  the 
draft  on  the  plant  would  be  such  as  to  "blow  " 
the  fuses.  For  instance,  all  the  baking  is  done 
in  daylight;  and  when  the  oven  is  used  after 
dark,  they  are  careful  to  turn  off  all  lights  not 
needed.  An 'ideal  plant,  of  course,  would  be 
a  plant  big  enough  to  take  care  of  the  sum 
of  lamps  and  handy  devices  used  at  one 
time. 

To  make  this  plant  ideal,  (for,  being  an 
actual  affair,  it  has  developed  some  short- 
comings, with  the  extension  of  the  use  of  elec- 
tricity) it  would  require  a  dynamo  whose 
capacity  can  be  figured,  from  the  following: 


134         ELECTRICITY  FOR  THE  FARM 

Watts 

15  carbon  lamps,  16  candlepower,  @60  watts  each 900 

10  tungsten  lamps,  20  candlepower,  @25  watts  each 250 

2  tungsten  lamps,  92  candlepower,  @100  watts  each .......  200 

Water  heater,  continuous  service 800 

Toaster,  occasional  service 600 

Iron,  occasional  service 400 

Oven-baking,  roasting,  etc 2,000 

2  stove  plates  @1,000  watts  each 2,000 

1  stove  plate 400 

Vacuum  cleaner,  occasional  service 200 

Vibrator,  occasional  service 100 

Small  water  heater,  quart  capacity 400 

Small  motor,  %  horsepower,  occasional 250 

Motor,  %  nP»  pumping  water,  etc 500 

Electric  fan,  occasional  service 100 

Total  current,  one  house 9,100 

30  carbon  lamps,  16  candlepower,  @60 1,800 

2  lamps,  100  watt  tungsten 200 

Electric  iron 400 

Small  water  or  milk  heater 600 


Total  current,  2nd  house 3,000 

1st  house..  9,100 


12,100 

Thus,  in  this  plant,  if  every  electrical  device 
were  turned  on  at  once,  the  demand  on  the 
dynamo  would  be  for  12.1  kilowatts,  or  an 
overload  of  over  100  per  cent.  The  main- 
switch  fuse,  being  for  60  amperes,  would 
"blow"  or  melt,  and  cut  off  all  current  for  the 


WHAT  SIZE  PLANT  TO  INSTALL        135 

moment.  To  repair  the  damage  would  be 
merely  the  work  of  a  second — and  at  a  cost 
of  a  few  cents — simply 
insert  a  new  fuse,  of 
which  there  must  be  a 
supply  on  hand  at  all 
times .  Or,  if  either  owner 
exceeded  his  capacity, 

the  line  fuses  (one  for  20     25  and  40  watt  Mazda  tung- 

amperes,  and  the  other         sten  lamps  (^  scale) 
for  40  amperes)  would  instantly  cut  off  all  cur- 
rent from  the  greedy  one. 

Lessons  From  This  Plant 

The  story  of  this  plant  illustrates  two  things 
which  the  farmer  and  his  wife  must  take  into 
account  when  they  are  figuring  how  much 
electricity  they  require.  First,  it  illustrates 
how  one  uses  more  and  more  current,  as  he 
finds  it  so  serviceable  and  labor-saving,  and 
at  the  same  time  free.  The  electric  range  and 
the  water  boiler,  in  the  above  instance,  were 
later  acquisitions  not  counted  on  in  figuring 
the  original  installation.  Second,  it  illustrates, 


136         ELECTRICITY  FOR  THE  FARM 

that  while  the  normal  load  of  this  generator  is 
5.75  kilowatts,  one  does  not  have  to  limit  the 
electrical  conveniences  in  the  home  to  this 
amount.  True,  he  cannot  use  more  electricity 
than  his  plant  will  produce  at  any  one  time, — 
but  it  is  only  by  a  stretch  of  the  imagination 
that  one  may  conceive  the  necessity  of  using 
them  all  at  once.  Ironing,  baking,  and  the  use 
of  small  power  are  usually  limited  to  daylight 
hours  when  no  lights  are  burning. 

As  a  matter  of  fact,  this  plant  has  proved 
satisfactory  in  every  way;  and  only  on  one 
or  two  occasions  have  fuses  been  "blown", 
and  then  it  was  due  to  carelessness.  A  modern 
dynamo  is  rated  liberally.  It  will  stand  an 
overload  of  as  much  as  100  per  cent  for  a 
short  time — half  an  hour  or  so.  The  danger 
from  overloading  is  from  heating.  When  the 
machine  grows  too  hot  for  the  hand,  it  is 
beginning  to  char  its  insulation,  to  continue 
which,  of  course  would  ruin  it.  The  best 
plant  is  that  which  works  under  one-half 
or  three-quarters  load,  under  normal  de- 
mands. 


WHAT  SIZE  PLANT  TO  INSTALL        137 

Standard  Voltage 

We  are  assuming  the  farmer's  plant  to  be, 
in  99  cases  out  of  100,  the  standard  110-volt, 
direct  current  type.  Such  a  plant  allows  for 
at  least  a  10  per  cent  regulation,  in  voltage, 
up  or  down  the  scale;  supplies  for  this  voltage 
are  to  be  had  without  delay  in  even  the  more 
remote  parts  of  the  country,  and  (being  sold 
in  greater  volume)  they  are  cheaper  than 
those  for  other  voltages. 

There  are  two  general  exceptions  to  this 
rule  as  to  110-volt  plants:  (1)  If  the  plant  is 
located  at  a  distance  greater  than  a  quarter 
of  a  mile  from  the  house,  it  will  be  found 
cheaper  (in  cost  of  transmission  line,  as  will 
be  shown  later)  to  adopt  the  220-volt  plant; 
(2),  If  the  water  supply  is  so  meagre  that  it 
must  be  stored  for  many  hours  at  a  time,  and 
then  used  for  charging  storage  batteries,  it 
will  be  found  most  economical  to  use  a  30-volt 
plant.  A  storage  battery  is  made  up  of  cells 
of  approximately  2  volts  each;  and,  since  more 
than  55  such  cells  would  be  required  for  a 


138         ELECTRICITY  FOR  THE  FARM 

110-volt  installation,  its  cost  would  be  pro- 
hibitive, with  many  farmers. 

So  we  will  assume  that  this  plant  is  a  110- 
volt  plant,  to  be  run  without  storage  battery. 
It  will  be  well  to  make  a  chart,  dividing  the 
farm  requirements  into  three  heads — light, 
heat,  and  power. 

Light 

Light  is  obtained  by  means  of  incandescent 
lamps.  There  are  two  styles  in  common  use, 


60  and  100  watt  Mazda  tungsten  lamp.    These  lamps  may  be  had 
in  sizes  from  10  to  500  watts     (%  scale) 

the  carbon  and  the  tungsten  lamp.  It  requires 
3.5  to  4  watts  of  electricity  to  produce  one 
candlepower  in  a  carbon  lamp.  It  requires 


WHAT  SIZE  PLANT  TO  INSTALL        139 


from  1  to  1.25  watt  to  produce  one  candlepower 
in  the  tungsten  lamp.  The  new  nitrogen  lamp, 
not  yet  in  general  use,  requires  only  J^  watt 
to  the  candlepower. 
Since  tungsten  lamps 
give  three  times  the 
light  of  the  carbon 
lamp,  they  are  the 
most  economical  to 
use  in  the  city  or 
town  where  one  is 
paying  for  commer- 
cial current.  But,  in 
the  country  where 
water-powerfurnishes 
current  for  nothing,  it 
will  be  found  most 
economical  to  use  the 
carbon  lamp,  since  its 

The  lamp  of  the  future.    A  1000 

COSt  at  retail  IS  16  watt  Mazda  nitrogen  lamp,  giving 
CentS,  as  Compared  «000  candlepower  (M  scale) 

with  30  cents  for  a  corresponding  size  in  tung- 
sten. A  60  watt  carbon  lamp,  of  16  candle- 
power;  or  a  25  watt  tungsten  lamp,  of  20 


140         ELECTRICITY  FOR  THE  FARM 

candlepower,  are  the  sizes  to  use.  In  hang- 
ing lamps,  as  over  the  dining  room  table, 
a  100  watt  tungsten  lamp,  costing  70  cents, 
and  giving  92  candlepower  light  is  very  de- 
sirable; and  for  lighting  the  barn-yard,  these 
100  watt  tungsten  lamps  should  be  used. 
For  reading  lamps,  the  tungsten  style,  of  40 
or  60  watt  capacity,  will  be  found  best.  Other- 
wise, in  all  locations  use  the  cheaper  carbon 
lamp.  Both  styles  have  a  rated  life  of  1,000 
hours,  after  which  they  begin  to  fall  off  in 
efficiency.  Here  again,  the  farmer  need  not 
worry  over  lack  of  highest  efficiency,  as  a 
lamp  giving  only  80  per  cent  of  its  rated 
candlepower  is  still  serviceable  when  he  is 
not  paying  for  the  current.  With  care  not 
to  use  them  at  voltages  beyond  their  ratings, 
lamps  will  last  for  years. 

A  Specimen  Light  Allowance 

Below  is  a  typical  table  of  lights  for  a  large 
farm  house,  the  barns  and  barn -yard.  It  is 
given  merely  as  a  guide,  to  be  varied  for  each 
individual  case: 


WHAT  SIZE  PLANT  TO  INSTALL  141 

Watts 

Kitchen,  2  lights  @60  watts 120 

Dining  room,  1  light,  tungsten 100 

Living  room,  table  lamp  with  3  tungstens  @40 120 

Living  room,  2  wall  fixtures,  4  lamps  @60  watts 240 

Parlor,  same  as  living  room 360 

Pantry,  1  hanging  lamp 60 

Cellar,  one  portable  lamp 60 

Woodshed,  1  hanging  lamp 60 

2  bedrooms,  2  lights  each  @  60 240 

2  bed  rooms,  1  light  each  @60 120 

Bathroom,  1  "turn-down"  light,  @60 60 

Hall,  downstairs,  2  lights  @60 120 

Hall,  upstairs,  1  light 60 

Attic,  1  light 60 

Porch,  1  light 60 

Bam  and  barn-yard: 

Barn-yard  entrance,  1  tungsten 100 

Watering  trough,      1        "           100 

Front  gate,                1        "           100 

Horse  bam,  4  lights  @60 240 

Cow  barn,  4  lights  @60 240 

Pig  house,  1  light 60 

Hay  bam,  2  lights,  @60 120 


Total  for  farmstead 2,800 

This  provides  for  44  lights,  an  extremely 
liberal  allowance.  How  many  of  these  lights 
will  be  burning  at  any  one  time?  Probably 
not  one-half  of  them;  yet  the  ideal  plant  is 
that  wrhich  permits  all  fixtures  to  be  in  serv- 
ice at  one  time  on  the  rare  occasions  when 
necessary.  Thus,  for  lighting  only,  2,800 


142         ELECTRICITY  FOR  THE  FARM 

watts  maximum  service  would  require  a 
4  kilowatt  generator,  and  10  water  horse- 
power, on  the  liberal  rating  of  two  to  one. 
A  3  kilowatt  generator  would  take  care  of 
these  lights,  with  a  30  per  cent  overload  (which 
is  not  excessive)  for  maximum  service.  The 
above  liberal  allowance  of  lights  may  be  cut 
in  two,  or  four — or  even  eight — and  still 
throw  a  kerosene  lamp  in  shadow.  It  all 
depends  on  the  number  of  lights  one  wants 
burning  at  one  time;  and  the  power  of  the 
water  wheel. 

If  the  36  carbon  lights  in  the  above  table 
were  replaced  by  25  watt  tungsten  lights, 
the  saving  in  power  would  be  35  watts  each, 
or  1,260  watts,  nearly  two  electrical  horse- 
power; while  the  added  first  cost  would  be 
14  cents  a  light,  or  $5.04.  A  generator  of 
2  kilowatt  capacity  would  take  care  of  all 
these  lights  then,  with  460  watts  to  spare. 

Heating 

Electric  heating  and  cooking  is  in  its  in- 
fancy, due  to  the  prohibitive  cost  of  com- 


WHAT  SIZE  PLANT  TO  INSTALL       143 

mercial  current  in  our  cities.  Here  the  far- 
mer has  the  advantage  again,  with  his  cheap 
current. 

For  heating  the  house,  it  is  calculated  that 
2  watts  is  required  for  each  cubic  foot  of 
air  space  in  a  room,  during  ordinary  winter 
weather.  Thus,  a  room  10  x  12,  and  8  feet 
high,  would  contain  960  cubic  feet,  and  would 
require  1,820  watts  energy  to  heat  it  in  cold 
weather.  Five  such  rooms  would  require 
9.1  kilowatts;  and  10  such  rooms,  or  their 
equivalent,  would  require  18.2  kilowatts. 

Electric  heating  devices  are  divided  into 
two  classes:  (1)  those  which  can  be  used  on 
lamp  circuits,  and  do  not  draw  more  than  660 
watts  each;  and  (2)  those  which  draw  more 
than  660,  therefore  require  special  wiring. 
The  capacity  of  these  devices  is  approximately 
as  follows: 

Lamp  circuit  devices:  Watts 

Electric  iron 400  to  660 

Toaster 350  to  660 

Vacuum  cleaner 200  to  400 

Grill 400  to  660 

Small  water  heater 400  to  660 

Hot  plates 400  to  660 


144         ELECTRICITY  FOR  THE  FARM 

Lamp  circuit  devices:  Watts 

Coffee  percolator 400  to  660 

Chafing  dish 400  to  660 

Electric  fan 100  to  250 

Special  circuit  devices: 

Hot  water  boiler  heater 800  to  1,200 

Small  ovens 660  to  1,200 

Range  ovens 1,200  to  3,000 

Range,  hot  plates 400  to  1,300 

Radiators  (small) 750  to  1,500 

Radiators(  large) 1,500  to  6,000 


The  only  device  in  the  above  list  which 
is  connected  continuously,  is  the  hot  water 
boiler,  and  this  can  be  credited  with  at  least 
one  electrical  horsepower  24  hours  a  day. 
It  is  a  small  contrivance,  not  much  bigger 
than  a  quart  can,  attached  to  the  back  of 
the  kitchen  boiler,  and  it  keeps  the  water 
hot  throughout  the  house  at  all  hours.  Its 
cost  will  vary  with  the  make,  ranging  from 
$8  to  $15;  and  since  it  is  one  of  the  real  bless- 
ings of  the  farm  kitchen  and  bathroom,  it 
should  be  included  in  all  installations  where 
power  permits.  Electric  radiators  will  be 
used  24  hours  a  day  in  winter,  and  not  at 
all  in  summer.  They  are  portable,  and  can 


WHAT  SIZE  PLANT  TO  INSTALL       145 

be  moved  from  room  to  room,  and  only  such 
rooms  as  are  in  actual  use  need  be  heated. 
The  other  devices  are  for  intermittent  serv- 
ice, many  of  them  (like  the  iron)  for  only  a 
few  hours  each  week. 

The  grill,  chafing  dish,  coffee  percolator, 
etc.,  which  are  used  on  the  dining  room  table 
while  the  family  is  at  meals,  each  draw  an 
equivalent  of  from  6  to  10  carbon  lights. 
By  keeping  this  in  view  and  turning  off  spare 
lights,  one  can  have  the  use  of  them,  with 
even  a  small  plant.  Thus,  a  one  kilowatt 
plant  permits  the  use  of  any  one  of  these 
lamp  circuit  devices  at  a  time,  with  a  few  lights 
in  addition. 

Power 

Electric  power  is  to  be  had  through  motors. 
A  direct  current  dynamo  and  a  direct  current 
motor  are  identical  in  construction.  That  is,  a 
motor  becomes  a  generator  if  belted  to  power; 
and  a  generator  becomes  a  motor,  if  connected 
to  electric  mains.  This  is  best  illustrated  by 
citing  the  instance  of  a  trans-continental 


146         ELECTRICITY  FOR  THE  FARM 

Main 


Connections  of  shunt  motor  and  starting  rheostat 

railroad  which  crosses  the  Bitter  Root  Moun- 
tains by  means  of  electric  power.  Running 
200  miles  up  a  2  per  cent  grade,  it  is  drawn 


WHAT  SIZE  PLANT  TO  INSTALL        147 

by  its  motors.  Coasting  200  miles  down  the 
2  per  cent  grade  on  the  other  side  of  the  moun- 
tains, its  motors  become  generators.  They 
act  as  brakes,  and  at  the  same  time  they 
pump  the  power  of  the  coasting  weight  of 
this  train  back  into  the  wires  to  help  a  train 
coming  up  the  other  side  of  the  moun- 
tains. 

Just  as  there  are  three  types  of  direct  cur- 
rent generators,  so  there  are  three  types  of 
direct  current  motors:  series,  shunt,  and 
compound,  with  features  already  explained 
in  the  case  of  generators.  Motors  are  rated 
by  horsepower,  and  generators  are  rated  by 
kilowatts.  Thus  a  one  kilowatt  generator 
has  a  capacity  of  1,000  watts;  as  a  motor,  it 
would  be  rated  as  *f££-  horsepower,  or  1.34 
horsepower.  Their  efficiency  varies  with  their 
size,  ranging  from  40  to  60  per  cent  in  very 
small  motors,  and  up  to  95  per  cent  in 
very  large  ones.  The  following  table  may 
be  taken  as  a  guide  in  calculating  the 
power  required  by  motors,  on  110-volt  cir- 
cuits: 


148        ELECTRICITY  FOR  THE  FARM 

34  Horsepower  2^  amperes,  or  275  watts 
]/2    hp  4^  amperes,  or' 500  watts 

1  hp  9  amperes,  or  990  watts 

2  hp  17  amperes,  or  1 . 97  kilowatts 

3  hp  26  amperes,  or  2 . 86  kilowatts 
5    hp  40  amperes,  or  4 . 40  kilowatts 

73^  hp  60  amperes,  or  6 . 60  kilowatts 

10    hp  76  amperes,  or  8 . 36  kilowatts 

15    hp  112  amperes,  or  12.32  kilowatts 


An  electric  motor,  in  operation,  actually 
generates  electricity,  which  it  pushes  back 
into  the  line  as  a  counter-electromotive-force. 
The  strength  of  this  counter  force,  in  volts, 
depends  on  the  motor's  speed,  the  same  as  if 
it  were  running  as  a  dynamo.  For  this  reason, 
when  a  motor  is  started,  and  before  it  comes 
up  to  speed,  there  would  be  a  rush  of  current 
from  the  line,  with  nothing  to  hold  it  back, 
and  the  motor  would  be  burned  out  unless 
some  means  were  provided  to  protect  it  for 
the  moment.  This  is  done  by  means  of  a 
starting  rheostat,  similar  to  the  regulating 
rheostat  on  the  dynamo  switchboard.  This 
resistance  box  is  connected  in  "series"  with 
the  armature,  in  the  case  of  shunt  and 
compound  motors;  and  with  the  entire 


WHAT  SIZE  PLANT  TO  INSTALL       149 

motor  circuit  in  the  case  of  a  series  ma- 
chine. 

A  series  motor  has  a  powerful  starting 
torque,  and  adjusts  its  speed  to  the  load. 
It  is  used  almost  altogether  in  street  cars. 
It  can  be  used  in  stump  pulling,  or  derrick 
work,  such  as  using  a  hay  fork.  It  must  al- 
ways be  operated  under  load,  otherwise,  it 
would  increase  in  speed  until  it  tore  itself 
to  pieces  through  mechanical  strain.  The 
ingenious  farmer  who  puts  together  an  elec- 
tric plow,  with  the  mains  following  behind 
on  a  reel,  will  use  a  series  motor. 

A  shunt  motor  should  be  used  in  all  situa- 
tions where  a  fairly  uniform  speed  under 
load  is  required,  such  as  separating,  in  milk- 
ing machines,  running  a  lathe,  an  ensilage 
cutter,  vacuum  cleaners,  grinders,  etc. 

The  compound  motor  has  the  characteristics 
of  the  series  and  shunt  motors,  giving  an 
increased  starting  torque,  and  a  more  nearly 
constant  speed  under  varying  loads  than  the 
shunt  motor,  since  the  latter  drops  off  slightly 
in  speed  with  increasing  load. 


150         ELECTRICITY  FOR  THE  FARM 

Flexible  Power 

An  electric  motor  is  an  extremely  satisfac- 
tory form  of  power  because  it  is  so  flexible. 
Thus,  one  may  use  a  five  horsepower  motor 
for  a  one  horsepower  task,  and  the  motor  will 
use  only  one  electrical  horsepower  in  current — 
just  enough  to  overcome  the  task  imposed  on 
it.  For  this  reason,  a  large-sized  motor  may 
be  used  for  any  operation,  from  one  requiring 
small  power,  up  to  its  full  capacity.  It  will 
take  an  overload,  the  same  as  a  dynamo.  In 
other  words  it  is  "eager"  for  any  task  imposed 
on  it;  therefore  it  must  be  protected  by  fuses, 
or  it  will  consume  itself,  if  too  big  an  overload 
is  imposed  on  it. 

A  one  horsepower  shunt  or  compound  motor 
is  very  serviceable  for  routine  farm  operations, 
such  as  operating  the  separator,  the  churn, 
the  milking  machine,  grinder,  pump,  and  other 
small  power  jobs.  Motors  of  J4  horsepower 
are  handy  in  the  kitchen,  for  grinding  knives, 
polishing  silver,  etc.,  and  can  be  used  also  for 
vacuum  cleaners,  and  running  the  sewing 


WHAT  SIZE  PLANT  TO  INSTALL       151 

machine.  For  the  larger  operations,  motors 
will  vary  from  three  horsepower  for  cutting 
ensilage,  to  fifteen  horsepower  for  threshing. 
They  can  be  mounted  on  trucks  and  conveyed 
from  one  point  to  another,  being  fed  current 
from  the  mains  by  means  of  suitable  wires 
wound  on  reels. 

Remember,  in  estimating  the  size  of  your 
plant  for  light,  heat,  and  power,  that  it  does  not 
have  to  be  big  enough  to  use  all  the  devices 
at  one  time.  Also  remember,  that  two  water 
horsepower  to  one  electrical  horsepower  is  a 
very  liberal  allowance;  and  that  a  generator 
working  under  one-half  or  two-thirds  capacity 
at  normal  loads  will  require  less  attention 
than  a  machine  constantly  being  worked 
above  its  capacity.  Therefore,  let  your 
generator  be  of  liberal  size,  because  the  differ- 
ence in  cost  between  a  5  and  10  kilowatt 
machine  is  not  in  proportion  to  their  capacity. 
In  fact  (especially  among  second-hand  ma- 
chines), the  difference  in  cost  is  very  small. 
The  mere  fact  that  the  generator  is  of  110 
electrical  horsepower  capacity  does  not  require 


152         ELECTRICITY  FOR  THE  FARM 

a  turbine  of  20  horsepower.  The  chances  are 
that  (unless  you  wish  to  heat  your  house  and 
do  large  power  jobs)  you  will  not  use  more 
than  3  to  5  electrical  horsepower  normally; 
therefore  an  allowance  of  10  water  horsepower, 
in  this  case,  would  be  ample.  A  plant  used 
simply  for  lighting  the  house  and  barn,  for 
irons,  and  toasters,  and  one  horsepower 
motors,  need  not  exceed  2  or  2 1/2  kilowatts  for 
the  generator,  and  5  or  6  horsepower  for  the 
turbine  wheel.  Normally  it  would  not  use 
one-half  this  capacity. 


CHAPTER  VII 

TRANSMISSION   LINES 

Copper  wire — Setting  of  poles — Loss  of  power  in  trans- 
mission— Ohm's  Law  and  examples  of  how  it  is 
used  in  figuring  size  of  wire — Copper- wire  tables — 
Examples  of  transmission  lines — When  to  use 
high  voltages — Over-compounding  a  dynamo  to 
overcome  transmission  loss. 

HAVING  determined  on  the  location  of  the 
farm  water-power  electric  plant,  and  its  capac- 
ity, in  terms  of  electricity,  there  remains  the 
wiring,  for  the  transmission  line,  and  the  house 
and  barn. 

For  transmission  lines,  copper  wire  covered 
with  waterproof  braid — the  so-called  weather- 
proof wire  of  the  trade — is  used.  Under  no 
circumstances  should  a  wire  smaller  than 
No.  8,  B.  &  S.  gauge  be  used  for  this  purpose, 
as  it  would  not  be  strong  enough  mechanically. 
The  poles  should  be  of  chestnut  or  cedar,  25 
feet  long,  and  set  four  feet  in  the  ground. 
Where  it  is  necessary  to  follow  highways,  they 

153 


154         ELECTRICITY  FOR  THE  FARM 

should  be  set  on  the  fence  line;  and  in  crossing 
public  highways,  the  ordinance  of  your  own 
town  must  guide  you.  Some  towns  prescribe 
a  height  of  19  feet  above  the  road,  others 
27  feet,  some  30.  Direct  current,  such  as  is 
advised  for  farm  installations,  under  ordinary 
circumstances,  does  not  affect  telephone  wires, 
and  therefore  transmission  lines  may  be  strung 
on  telephone  poles.  Poles  are  set  at  an 
average  distance  of  8  rods;  they  are  set  in- 
clined outward  on  corners.  Sometimes  it  is 
necessary  to  brace  them  with  guy  wires  or 
wooden  braces.  Glass  insulators  are  used  to 
fasten  the  wires  to  the  cross-arms  of  the  poles, 
and  the  tie-wires  used  for  this  purpose  must 
be  the  same  size  as  the  main  wire  and  carry 
the  same  insulation. 

Size  of  Wire  for  Transmission 

To  determine  the  size  of  the  transmission 
wires  will  require  knowledge  of  the  strength 
of  current  (in  amperes)  to  be  carried,  and  the 
distance  in  feet.  In  transmission,  the  electric 
current  is  again  analogous  to  water  flowing  in 


TRANSMISSION  LINES 


155 


pipes.  It  is  subject  to  resistance,  which  cuts 
down  the  amount  of  current  (in  watts)  deliv- 
ered. 

The  loss  in  transmission  is  primarily  meas- 
ured in  volts;  and  since  the  capacity  of  an 
electric  current  for  work  equals  the  volts 


A~  GLA&S  INSULATOR, 

3~  Z>AZP  LOOP 

C—    EffTRAATGE  ^SWITCH 

D~  SWITCH  KfiNEL  FOR.  HOUSE  SE&I/7CE 

E  -   PORCELAIN  TUBE&    F~FUSB  PLUG* 

Bringing  wires  into  the  house  or  barn 


multiplied  by  amperes,  which  gives  watts, 
every  volt  lost  reduces  the  working  capacity 
of  the  current  by  so  much.  This  loss  is  referred 
to  by  electrical  engineers  as  the  "C2  R  loss," 
which  is  another  way  of  saying  that  the  loss  is 
equal  to  the  square  of  the  current  in  amperes, 
multiplied  by  ohms  resistance.  Thus,  if  the 


156        ELECTRICITY  FOR  THE  FARM 

amperes  carried  is  10,  and  the  ohms  resistance 
of  the  line  is  5,  then  the  loss  in  watts  to  convey 
that  current  would  be  (10  x  10)  x  5,  or  500 
watts,  nearly  a  horsepower. 

The  pressure  of  one  volt  (as  we  have  seen  in 
another  chapter)  is  sufficient  to  force  one 
ampere,  through  a  resistance  of  one  ohm.  Such 
a  current  would  have  no  capacity  for  work, 
since  its  pressure  would  be  consumed  iix  the 
mere  act  of  transmission. 

If,  however,  the  pressure  were  110  volts, 
and  the  current  one  ampere,  and  the  resistance 
one  ohm,  the  effective  pressure  after  transmis- 
sion would  be  110— 1,  or  109  volts. 

To  force  a  110-volt  current  of  50  amperes 
through  the  resistance  of  one  ohm,  would  re- 
quire the  expenditure  of  50  volts  pressure.  Its 
capacity  for  work,  after  transmission,  would 
be  110—50,  or  60  volts,  x  50  amperes,  or  3,000 
watts.  As  this  current  consisted  of  110  x  50, 
or  5,500  watts  at  the  point  of  starting,  the  loss 
would  be  2,500  watts,  or  about  45  per  cent. 
It  is  bad  engineering  to  allow  more  than  10  per 
cent  loss  in  transmission. 


TRANSMISSION  LINES  157 

There  are  two  ways  of  keeping  this  loss 
down.  One  is  by  increasing  the  size  of  the 
transmission  wires,  thus  cutting  down  the 
resistance  in  ohms;  the  other  way  is  by  raising 
the  voltage,  thus  cutting  down  the  per  cent 
loss.  For  instance,  suppose  the  pressure  was 
1,100  volts,  instead  of  110  volts.  Five  amperes 
at  1,100  volts  pressure,  gives  the  same  number 
of  watts,  power,  as  50  amperes,  at  110  volts 
pressure.  Therefore  it  would  be  necessary  to 
carry  only  5  amperes,  at  this  rate.  The  loss 
would  be  5  volts,  or  less  than  ^  of  1  per  cent, 
as  compared  with  45  per  cent  with  110  volts. 

In  large  generating  stations,  where  individ- 
ual dynamos  frequently  generate  as  much  as 
20,000  horsepower,  «==^SSSssss3&2>=s 

and  the  Current  must  Splicing  transmission  wire 

be  transmitted  over  several  hundred  miles  of 
territory,  the  voltage  is  frequently  as  high  as 
150,000,  with  the  amperes  reduced  in  propor- 
tion. Then  the  voltage  is  lowered  to  a  suitable 
rate,  and  the  amperage  raised  in  proportion,  by 
special  machinery,  at  the  point  of  use. 

It  is  the  principle  of  the  C2R  loss,  which  the 


158          ELECTRICITY  FOR  THE  FARM 

farmer  must  apply  in  determining  the  size  of 
wire  he  is  to  use  in  transmitting  his  current 
from  the  generator  switchboard  to  his  house 
or  barn.  The  wire  table  on  page  159,  together 
with  the  formula  to  be  used  in  connection 
with  it,  reduce  the  calculations  necessary  to 
simple  arithmetic.  In  this  table  the  resistance 
of  the  various  sizes  of  wire  is  computed  from 
the  fact  that  a  wire  of  pure  copper  1  foot  long, 
and  1/1000  inch  in  diameter  (equal  to  one 
circular  mill)  offers  a  resistance  of  10.6  ohms 
to  the  foot.  The  principle  of  the  C2R  loss  is 
founded  on  Ohm's  Law,  which  is  explained  in 
Chapter  V. 

The  formula  by  which  the  size  of  trans- 
mission wire  is  determined,  for  any  given 
distance,  and  a  given  number  of  amperes, 
is  as  follows: 

Distance  ft.  one  way  x  %%  x  No.  of  amperes  _  circular 
Number  of  volts  lost  mills. 

In  other  words,  multiply  the  distance  in 
feet  from  mill  to  house  by  22,  and  multiply 
this  product  by  the  number  of  amperes  to  be 


COPPER  WIRE  TABLE 


B.  &S. 
Gauge 

Feet 
per  Lb. 

Area  in 
circular 
mills 

(R)  Ohms 
per  1,000 
feet 

Feet 
per  Ohm 

(R)  Ohms 
per  pound 

0000 

1.561 

211,600 

.04904 

20,392.90 

.00007653 

000 

1.969 

167,805 

.06184 

16,172.10 

.00012169 

00 

2.482 

133,079 

.07797 

12,825.40 

.00019438 

0 

3.130 

105,534 

.09829 

10,176.40 

.00030734 

1 

3.947 

83,694 

.  12398 

8,066.00 

.00048920 

2 

4.977 

66,373 

.  15633 

6,396.70 

.00077784 

3 

6.276 

52,634 

.19714 

5,072.50 

.00123700 

4 

7.914 

41,742 

.24858 

4,022.90 

.00196660 

5 

9.980 

33,102 

.31346 

3,190.20 

.00312730 

6 

12.58 

26,250 

.39528 

2,529.90 

.00497280 

7 

15.87 

20,816 

.49845 

2,006.20 

.00790780 

8 

20.01 

16,509 

.62840 

1,591.10 

.01257190 

9 

25.23 

13,094 

.79242 

1,262.00 

.  01998530 

10 

31.82 

10,381 

.99948 

1,000.50 

.03178460 

11 

40.12 

8,234.0 

1  26020 

793.56 

.05054130 

12 

50.59 

6,529.9 

1.58900 

629.32 

.08036410 

13 

63.79 

5,178.4 

2.00370 

499.06 

.  12778800 

14 

80.44 

4,106.8 

2.52660 

395.79 

.20318000 

15 

101.4 

3,256.7 

3.18600 

313.87 

.32307900 

16 

127.9 

2,582.9 

4.01760 

248.90 

.51373700 

17 

161.3 

2,048.2 

5.06600 

197.39 

.81683900 

18 

203.4 

1,624.3 

6.38800 

156.54 

1.29876400 

CARRYING  CAPACITY  OF  WIRES  AND  WEIGHT 


B.  &S. 
Gauge  No. 

Weight  1,000  //. 
Weatherproof 
(Pounds) 

Carrying  capacity 
Weatherproof 
(Amperes) 

Carrying  capacity 
rubber  cov. 
(Amperes) 

0000 

800 

312 

175 

000 

666 

262 

145 

00 

500 

220 

120 

0 

363 

185 

100 

1 

313 

156 

95 

2 

250 

131 

70 

3 

200 

110 

60 

4 

144 

92 

50 

5 

125 

77 

45 

6 

105 

65 

85 

7 

87 

55 

30 

8 

69 

46 

25 

10 

50 

32 

20 

12 

31 

23 

15 

14 

22 

16 

10 

16 

14 

8 

5 

18 

11 

5 

3 

159 


160         ELECTRICITY  FOR  THE  FARM 

carried.  Then  divide  the  product  by  the 
number  of  volts  to  be  lost;  and  the  result  will 
be  the  diameter  of  the  wire  required  in  circu- 
lar mills.  By  referring  to  the  table  above, 
the  B.  &  S.  gauge  of  the  wire  necessary  for 
transmission,  can  be  found  from  the  nearest 
corresponding  number  under  the  second  col- 
umn, entitled  "circular  mills  area." 

Since  two  wires  are  required  for  electrical 
transmission,  the  above  formula  is  made 
simple  by  counting  the  distance  only  one 
way,  in  feet,  and  doubling  the  resistance 
constant,  10.6,  which,  for  convenience  is 
taken  as  22,  instead  of  21.2. 

Examples  of  Transmission  Lines 

As  an  example,  let  us  say  that  Farmer 
Jones  has  installed  a  water-power  electric 
plant  on  his  brook,  200  yards  distant  from 
his  house.  The  generator  is  a  5  kilowatt 
machine,  capable  of  producing  1+5  amperes  at 
110  volts  pressure.  He  has  a  3  horsepower 
motor,  drawing  26  amperes  at  full  load;  he 
has  20  lights  of  varying  capacities,  requiring 


TRANSMISSION  LINES  161 

1,200  watts,  or  10  amperes  when  all  on;  and 
his  wife  uses  irons,  toasters,  etc.,  which  amount 
to  another  9  or  10  amperes — say  45  altogether. 
The  chances  are  that  he  will  never  use  all 
of  the  apparatus  at  one  time;  but  for  flexi- 
bility, and  his  own  satisfaction  in  not  having 
to  stop  to  think  if  he  is  overloading  his  wires, 


Transmission  wire  on  glass  insulator 

he  would  like  to  be  able  to  draw  the  full  1*5 
amperes  if  he  wishes  to.  He  is  willing  to 
allow  5  per  cent  loss  in  transmission.  What 
size  wires  will  be  necessary,  and  what  will  they 
cost?  Substituting  these  values  in  the  above 
formula,  the  result  is: 


Answer:  600  x  22  x  45      ,AOAnrt    .      ,         .„ 

— =  108,000  circular  mills. 

o.o 


Referring  to  the  table,  No.  0  wire  is  105,534 
circular  mills,  and  is  near  enough;  so  this  wire 
would  be  used.  It  would  require  1,200  feet, 


162         ELECTRICITY  FOR  THE  FARM 

which  would  weigh,  by  the  second  table,  435.6 
pounds.  At  19  cents  a  pound,  it  would  cost 
$82.76. 

Farmer  Jones  says  this  is  more  money  than 
he  cares  to  spend  for  transmission.  As  a 
matter  of  fact,  he  says,  he  never  uses  his  motor 
except  in  the  daytime,  when  his  lights  are 
not  burning;  so  the  maximum  load  on  his 
line  at  any  one  time  would  be  26  amperes, 
not  45.  What  size  wire  would  he  use  in  this 
instance? 

Substituting  26  for  45  in  the  equation, 
the  result  is  61,300  circular  mills,  which  corre- 
sponds to  No.  2  wire.  It  would  cost  $57.00. 

Now,  if  Farmer  Jones,  in  an  emergency, 
wished  to  use  his  motor  at  the  same  time  he 
was  using  all  his  lights  and  his  wife  was  iron- 
ing and  making  toast — in  other  words,  if 
he  wanted  to  use  the  45  amperes  capacity 
of  his  dynamo,  how  many  volts  would  he  lose? 
To  get  this  answer,  we  change  the  formula 
about,  until  it  reads  as  follows: 

Distance  in  feet  x  22  x  amperes      XT      ,        .      ,     , 

-. i TH =  Number  of  volts  lost 

circular  mills 


TRANSMISSION  LINES  163 

Substituting  values,  we  have,  in  this  case, 
600  x  22x45 

66,373  (No.  2)  =  9  V°ltS'  nearly'  leSS  th&n  10 
per  cent.  This  is  a  very  efficient  line,  under 
the  circumstances.  Now  if  he  is  willing  to 
lose  10  per  cent  on  half -load,  instead  of  full 
load,  he  can  save  still  more  money  in  line  wire. 
In  that  case  (as  you  can  find  by  applying  the 
formula  again),  he  could  use  No.  5  wire,  at  a 
cost  of  $28.50.  He  would  lose  11  volts  pres- 
sure drawing  26  amperes;  and  he  would  lose 
18  volts  pressure  drawing  45  amperes,  if  by 
any  chance  he  wished  to  use  full  load. 

In  actual  practice,  this  dynamo  would  be 
regulated,  by  means  of  the  field  resistance,  to 
register  110  plus  11  volts,  or  121  volts  at 
the  switchboard  to  make  up  for  the  loss  at 
half -load.  At  full  load,  his  voltage  at 
the  end  of  the  line  would  be  121  minus  18, 
or  103  volts;  his  motor  would  run  a  shade 
slower,  at  this  voltage,  and  his  lights  would 
be  slightly  dimmer.  He  would  probably 
not  notice  the  difference.  If  he  did,  he  could 
walk  over  to  his  generating  station,  and  raise 


164 


ELECTRICITY  FOR  THE  FARM 


the  voltage  a  further  7  volts  by  turning  the 

rheostat  handle  another  notch. 

Thousands  of  plants  can  be  located  within 

100  feet  of  the  house. 
If  Farmer  Jones  could 
do  this,  he  could  use 
No.  8  wire,  costing 
$2.62.  The  drop  in 
pressure  would  be  5.99 
volts  at  full  load — so 
small  it  could  be  ig- 
nored entirely.  In  this 
case  the  voltmeter 
should  be  made  to 
read  116  volts  at  the 
switchboard,  by  means 

A  barn-yard  light  „     ,         , 

or  the  rheostat. 

If,  on  the  other  hand,  this  plant  were  1,000 
feet  away  from  the  house  and  the  loss  10  volts 

1,000  x  22  x  45 


the    size    wire    would    be 


10 


99,000  circular  mills;  a  No.  0  wire  comes 
nearest  to  this  figure,  and  its  cost,  for  2,000 
feet,  at  19  cents  a  pound,  would  be  $137.94. 


TRANSMISSION  LINES  165 

A  No.  0000  wire,  costing  $294.00,  would  give 
a  5  per  cent  drop  at  full  load.  In  this  case, 
the  cost  of  transmission  can  be  reduced  to  a 
much  lower  figure,  by  allowing  a  bigger  drop 
at  half-load,  with  regulation  at  the  switch- 
board. Thus,  a  No.  2  wire  here,  costing  but 
$95,  would  be  satisfactory  in  every  way. 
The  loss  at  half-load  would  be  about  9  volts, 
and  the  rheostat  would  be  set  permanently 
for  119  or  120  volts.  A  modern  dynamo  can 
be  regulated  in  voltage  by  over  25  per  cent 
in  either  direction,  without  harm,  if  care  is 
taken  not  to  overload  it. 

Benefit  of  Higher  Voltages 

If  Farmer  Jones'  plant  is  a  half  of  a  mile 
away  from  the  house,  he  faces  a  more  serious 
proposition  in  the  way  of  transmission.  Say 
he  wishes  to  transmit  26  amperes  with  a  loss 
of  10  volts.  What  size  wire  will  be  necessary? 

2640  x  22  x  26 
Thus:  -JQ—       -  =  151,000  circular  mills. 

A  No.  000  wire  is  nearest  this  size,  and  5,280 
feet  of  it  would  cost  over  $650.00.  This  cost 


166         ELECTRICITY  FOR  THE  FARM 

would  be  prohibitive.  If,  however,  he  in- 
stalled a  220-volt  dynamo — at  no  increase 
in  cost — then  he  would  have  to  transmit 
only  a  half  of  26  amperes,  or  13  amperes, 
and  he  could  allow  22  volts  loss,  counting  10 
per  cent.  In  this  case,  the  problem  would 
work  out  as  follows: 

2640  x  22  x  13      Q.  QOA    .      ,          .„ 

-  =  34,320  circular  mills,  or  ap- 
proximately a  No.  5  wrire  which,  at  19  cents 
a  pound,  would  cost  $120.65. 

Install  a  550-volt  generator,  instead  of  a 
220-volt  machine  and  the  amperes  necessary 
would  be  cut  to  5.2,  and  the  volts  lost  would 
be  raised  to  55.  In  this  case  a  No.  12  wire 
would  carry  the  current;  but  since  it  would 
not  be  strong  enough  for  stringing  on  poles,  a 
No.  8  wire  would  be  used,  costing  about 
$63. 

It  will  be  readily  seen  from  these  examples 
how  voltage  influences  the  efficiency  of  trans- 
mission. Current  generated  at  a  pressure  in 
excess  of  550  volts  is  not  to  be  recommended 
for  farm  plants  unless  an  expert  is  in  charge. 


TRANSMISSION  LINES  167 

A  safer  rule  is  not  to  exceed  220  volts,  for 
while  550  volts  is  not  necessarily  deadly,  it  is 
dangerous.  When  one  goes  into  higher  volt- 
ages, it  is  necessary  to  change  the  type  of 
dynamo  to  alternating  current,  so  that  the 
current  can  be  transformed  to  safe  voltages 
at  the  point  where  it  is  used.  Since  only  the 
occasional  farm  plant  requires  a  high-tension 
system,  the  details  of  such  a  plant  will  not  be 
gone  into  here. 

In  transmitting  the  electric  current  over 
miles  of  territory,  engineers  are  accustomed  to 
figure  1,000  volts  for  each  mile.  Since  this  is  a 
deadly  pressure,  it  should  not  be  handled  by 
any  one  not  an  expert,  which,  in  this  case,  the 
farmer  is  not. 

Over -Compounding  the  Generator 

One  can  absorb  the  loss  in  transmission  fre- 
quently, by  over-compounding  the  machine. 
In  describing  the  compound  machine,  in 
Chapter  Five,  it  is  shown  that  the  usual  com- 
pound dynamo  on  the  market  is  the  so-called 
flat-compounded  type.  In  such  a  dynamo,  the 


168        ELECTRICITY  FOR  THE  FARM 

voltage  remains  constant  at  the  switchboard, 
from  no  load  to  full  load,  allowing  for  a  slight 
curve  which  need  not  be  taken  into  account. 

Now,  by  adding  a  few  more  turns  to  the 
series  wires  on  the  field  coils  of  such  a  dynamo, 
a  machine  is  to  be  had  which  gradually  raises 
its  voltage  as  the  load  comes  on  in  increasing 
volume.  Thus,  one  could  secure  such  a  ma- 
chine, which  would  begin  generating  at  110 
volts,  and  would  gradually  rise  to  150  at  full 
load.  Yet  the  voltage  would  remain  constant 
at  the  point  of  use,  the  excess  being  absorbed 
in  transmission.  A  machine  of  this  type  can 
be  made  to  respond  to  any  required  rise  in 
voltage. 

As  an  example  of  how  to  take  advantage  of 
this  very  valuable  fact,  let  us  take  an  in- 
stance: 

Say  that  Farmer  Jones  has  a  transmission 
line  1,000  feet  long  strung  with  No.  7  copper 
wire.  This  2,000  feet  of  wire  would  introduce 
a  resistance  of  one  ohm  in  the  circuit.  That 
is,  every  ampere  of  current  drawn  at  his  house 
would  cause  the  working  voltage  there  to  fall 


TRANSMISSION  LINES  169 

one  volt.  If  he  drew  26  amperes,  the  voltage 
would  fall,  at  the  house,  26  volts.  If  his 
switchboard  voltage  was  set  ;at  say  120,  the 
voltage  at  his  house,  at  26  amperes  of  load, 
would  fall  to  94  volts,  which  would  cause  his 
lights  to  dim  considerably.  It  would  be  a  very 
unsatisfactory  transmission  line,  with  a  flat- 
compounded  dynamo. 

On  the  other  hand,  if  his  dynamo  was  over- 
compounded  25  per  cent — that  is,  if  it  gained 
28  volts  from  no  load  to  full  load,  the  system 
would  be  perfect.  In  this  case,  the  dynamo 
would  be  operated  at  110  volts  pressure  at  the 
switchboard  with  no  load.  At  full  load  the 
voltmeter  would  indicate  110  plus  26,  or  136 
volts.  The  one  or  two  lights  burned  at  the 
power  plant  would  be  subject  to  a  severe 
strain;  but  the  50  or  100  lights  burned  at  the 
house  and  barn  would  burn  at  constant  volt- 
age, which  is  very  economical  for  lamps. 

The  task  of  over-compounding  a  dynamo 
can  be  done  by  any  trained  electrician.  The 
farmer  himself,  if  he  progresses  far  enough  in 
his  study  of  electricity,  can  do  it.  It  is  neces- 


170        ELECTRICITY  FOR  THE  FARM 

sary  to  remove  the  top  or  "series"  winding 
from  the  field  coils.  Count  the  number  of 
turns  of  this  wire  to  each  spool.  Then  procure 
some  identical  wire  in  town  and  begin  experi- 
menting. Say  you  found  four  turns  of  field 
wire  to  each  spool.  Now  wind  on  five,  or  six, 
being  careful  to  wind  it  in  the  same  direction 
as  the  coils  you  removed  and  connect  it  in  the 
same  way.  If  this  additional  number  of 
turns  does  not  raise  the  voltage  enough,  in 
actual  practice,  when  the  dynamo  is  running 
from  no  load  to  full  load,  add  another  turn  or 
two.  With  patience,  the  task  can  be  done  by 
any  careful  mechanic.  The  danger  is  in  not 
winding  the  coils  the  same  way  as  before,  and 
getting  the  connections  wrong.  To  prevent 
this  mistake,  make  a  chart  of  the  "  series  "  coils 
as  you  take  them  off. 

To  make  the  task  of  over-compounding 
your  own  dynamo  even  more  simple,  write  to 
the  manufacturers,  giving  style  and  factory 
number  of  your  machine.  Tell  them  how 
much  voltage  rise  you  wish  to  secure,  and  ask 
them  how  many  turns  of  "series"  wire  should 


TRANSMISSION  LINES  171 

be  wound  on  each  spool  in  place  of  the  old 
"series"  coil.  They  could  tell  you  exactly, 
since  they  have  mathematical  diagrams  of 
each  machine  they  make. 

Avoid  overloading  an  over-compounded  ma- 
chine. Since  its  voltage  is  raised  automat- 
ically, its  output  in  watts  is  increased  a  similar 
amount  at  the  switchboard,  and,  for  a  given 
resistance,  its  output  in  amperes  would  be 
increased  the  same  amount,  as  can  be  ascer- 
tained by  applying  Ohm's  Law.  Your  ammeter 
is  the  best  guide.  Your  machine  is  built  to 
stand  a  certain  number  of  amperes,  and  this 
should  not  be  exceeded  in  general  practice. 


CHAPTER  VIII 

WIRING    THE    HOUSE 

The  insurance  code — Different  kinds  of  wiring  de- 
scribed— Wooden  moulding  cheap  and  effective — 
The  distributing  panel — Branch  circuits — Pro- 
tecting the  circuits — The  use  of  porcelain  tubes 
and  other  insulating  devices — Putting  up  chande- 
liers and  wall  brackets — "Multiple"  connec- 
tions— How  to  connect  a  wall  switch — Special 
wiring  required  for  heat  and  power  circuits — 
Knob  and  cleat  wiring,  its  advantages  and  draw- 
backs. 

THE  task  of  wiring  your  house  is  a  simple 
one,  with  well-defined  rules  prescribed  by  your 
insurance  company.  Electricity,  properly  in- 
stalled, is  much  safer  than  oil  lamps — so 
much  so  indeed  that  insurance  companies  are 
ready  to  quote  especial  rates.  But  they  re- 
quire that  the  wiring  be  done  in  accordance 
with  rules  laid  down  by  their  experts,  who  form 
a  powerful  organization  known  as  the  National 
Board  of  Fire  Underwriters.  Ask  your  in- 
surance agent  for  a  copy  of  the  code  rules. 

172 


WIRING  THE  HOUSE  173 

Danger  of  fire  from  an  electric  current 
comes  from  the  "short  circuit,"  partial  or 
complete;  and  it  is  against  this  danger  that  the 
rules  guard  one.  The  amount  of  electricity 
flowing  through  a  short  circuit  is  limited  only 
by  the  fuse  protecting  that  line;  and  since 
there  is  no  substance  known  that  can  with- 
stand the  heat  of  the  electric  arc,  short 
circuits  must  be  guarded  against.  Happily 
the  current  is  so  easily  controlled  that  the 
fire  hazard  is  eliminated  entirely — something 
which  cannot  be  done  with  oil  lamps. 

In  house-wiring  for  farm  plants,  the  wire 
should  be  rubber-covered,  and  not  smaller 
than  No.  14  B.  &  S.  gauge.  This  is  the  wire  to 
use  on  all  lamp  circuits.  It  costs  about 
$0.85  cents  per  100  feet.  There  are  four  kinds 
of  wiring  permitted,  under  the  insurance  code: 

(1)  Flexible  armoured  cable:  This  consists  of 
two-wire  cable,  protected  with  a  covering  of 
flexible  steel.  It  is  installed  out  of  sight 
between  the  walls,  and  provides  suitable  out- 
lets for  lamps,  etc.,  by  means  of  metal  boxes 


174         ELECTRICITY  FOR  THE  FARM 

set  flush  with  the  plaster.  It  is  easily  installed 
in  a  house  being  built,  but  requires  much 
tearing  down  of  plaster  for  an  old  house. 
Since  its  expense  prohibits  it  in  the  average 
farm  house,  this  system  will  not  be  described 
in  detail  here. 

(2)  Rigid  and  flexible  conduit:  As  the  name 
implies  this  system  consists  of  iron  pipe,  in 
connection  with  flexible  conduit,  run  between 
the  walls.  It  differs  from  the  above  system,  in 
that  the  pipes  with  their  fittings  and  outlet 
boxes  are  installed  first,  and  the  wires  are 
then  "fished"  through  them.  Duplex  wires — 
the  two  wires  of  the  circuit  woven  in  one 
braid — are  used;  and  a  liberal  amount  of 
soapstone,  and  occasionally  kerosene,  are 
used  to  make  the  wires  slip  easily  into  place. 
This  is  the  most  expensive  system,  and 
the  best;  but  it  is  difficult  to  install  it  in 
an  old  house  without  tearing  down  a  good 
deal  of  plaster.  It  has  the  advantage 
of  being  absolutely  waterproof  and  fire- 
proof. 


WIRING  THE  HOUSE  175 

(3)  Wooden  moulding:  This  is  simply  mould- 
ing, providing  two  raceways  for  the  insulated 
wires  to  run  in,  and  covered  with  a  capping. 
It  is  nailed  or  screwed  firmly  to  the  wall,  on 
top    of    the    plaster;    and 

when  the  wires  have  been 
installed  in  their  respec- 
tive  slots  and  the  capping 
tacked  on,  the  moulding  is 

given    a    COat    of    paint    to    DetaU  of  wooden  moulding 

make  it  in  harmony  with  the  other  moulding 
in  the  room.  This  system  is  cheap,  safe,  and 
easily  installed,  and  will  be  described  in  detail 
here. 

(4)  Open  wiring:  In  open  wiring,  the  wires 
are  stretched  from  one  support  to  another 
(such  as  beams)  and  held  by  means  of  porce- 
lain cleats,  or  knobs.     It  is  the  simplest  to 
install;  but  it  has  the  objection  of  leaving  the 
wires  unprotected,  and  is  ugly.     It  is  very 
satisfactory  hi  barns   or  out-buildings  how- 
ever. 


176         ELECTRICITY  FOR  THE  FARM 

The  Distributing  Panel 

The  first  point  to  consider  in  wiring  a  house 
with  wooden  moulding  is  the  distribution 
board..  It  should  be  located  centrally,  on  the 
wall  near  the  ceiling,  so  as  to  be  out  of  ordinary 
reach.  It  consists  of  a  panel  of  wood — though 
fireproof  material  is  better — firmly  screwed  to 

the  wall,  and  contain- 
ing in  a  row,  the  por- 
c  e  1  a  i  n  cut-outs,  as 
shown  in  the  cut,  from 

Porcelain  cut-out  and  plug  fuse    ^^      f  >^     v  a  T  i  O  U  S 


branch  circuits  are  to  be  led.  Each  cut- 
out provides  for  two  branch  circuits;  and 
each  branch  contains  receptacles  for  two  plug 
fuses.  These  fuses  should  be  of  6  amperes 
each.  The  Insurance  Code  limits  the  amount 
of  electricity  that  may  be  drawn  on  any 
branch  lamp  circuit  to  660  watts;  and  these 
fuses  protect  the  circuit  from  drafts  beyond 
this  amount. 

The    mains,    leading    from    the    entrance 
switch,  as  shown  in  the  diagram,  to  the  panel 


WIRING  THE  HOUSE  177 

board,  should  be  of  the  same  size  as  the  trans- 
mission wire  itself,  and  rubber-covered.  These 
mains  terminate  at  the  distributing  board. 
They  are  connected  to  the  terminals  of  the 
cut-outs  by  means  of  heavy  brass  screws. 

Wire  Joints 

The  branch  circuits  are,  as  has  been  said, 
of  No.  14  rubber-covered  wire,  running  con- 


Examples  of  cleat  and  knob  wiring,  1,  2,  3;  wire  joints,  4; 
flexible  armoured  conductor,  5 

cealed  in  wooden  moulding.  All  joints  or 
splices  in  this  wire  are  made,  as  shown  in  the 
illustration,  by  first  scraping  the  wires  bright, 
and  fastening  them  stoutly  together.  This 
joint  is  then  soldered,  to  make  the  connection 
electrically  perfect.  Soft  solder  is  used,  with 


178        ELECTRICITY  FOR  THE  FARM 

ordinary  soldering  salts.  There  are  several 
compounds  on  the  market,  consisting  of  soft 
solder  in  powder  form,  ready-mixed  with  flux. 
Coat  the  wire  joint  with  this  paste  and  apply 
the  flame  of  an  alcohol  lamp.  The  soldered 
joint  is  then  covered  with  rubber  tape,  and 
over  this  ordinary  friction  tape  is  wound  on. 
A  neat  joint  should  not  be  larger  than  the 
diameter  of  the  wire  before  insulation  is  re- 
moved. 

Branch  Circuits 

First,  make  a  diagram  of  your  rooms  and 
indicate  where  you  wish  lamps,  or  outlets  for 
other  purposes.  Since  wooden  moulding  can 
be  run  across  ceilings,  and  up  or  down  walls, 
lamps  may  be  located  in  places  where  they 
are  out  of  the  way.  In  planning  the  circuit, 
remember  that  you  will  want  many  outlets 
in  handy  places  on  the  walls,  from  which 
portable  cords  will  convey  current  to  table 
lamps,  to  electric  irons  and  toasters  and  other 
handy  devices  which  can  be  used  on  the  lamp 
circuit.  These  outlets  are  made  of  porcelain, 


WIRING  THE  HOUSE  179 

in  two  pieces.  One  piece  is  merely  a  continua- 
tion of  the  moulding  itself;  and  the  other  is  a 
cap  to  connect  permanently  te  the  end  of  the 
lamp  or  iron  cord,  which  may  be  snapped  into 
place  in  a  second.  Since  there  are  a  great 
many  designs  of  separable  current  taps  on 
the  market,  it  is  well  to  select  one  design  and 
stick  to  it  throughout  the  house,  so  that  any 
device  can  be  connected  to  any  outlet. 

The  code  permits  660  watts  on  each  circuit. 
This  would  allow  12  lamps  of  55  watts  each. 
It  is  well  to  limit  any  one  circuit  to  6  lamps; 
this  will  give  leeway  for  the  use  of  small  stoves, 
irons,  toasters,  etc.  without  overloading  the 
circuit  and  causing  a  fuse  to  blow. 

Having  installed  your  distributing  board, 
with  its  cut-outs,  figure  out  the  course  of  your 
first  branch  circuit.  Let  us  say  it  will  provide 
lights  and  outlets  for  the  dining  room  and 
living  room.  It  will  be  necessary  to  run  the 
wires  through  the  partitions  or  floors  in  several 
places.  For  this  purpose  porcelain  tubes 
should  be  used,  costing  one  to  three  cents  each. 
Knock  holes  in  the  plaster  at  the  determined 


180         ELECTRICITY  FOR  THE  FARM 

point,  insert  the  tubes  so  they  project  %  inch 
on  each  side,  and  fill  up  the  ragged  edge  of  the 
hole  neatly  with  plaster. 


PORCBLAIH  GUT-OUTS 
CO -MAINS  TO  ENTRANCE  SWITCH 
DDD- BRANCH  LAMP  CIRCUITS 
IN  WOODEN  MOLDING- 
FFF  ~  FU<5E  PLUGS 

The  distributing  panel 

When  all  the  tubes  have  been  set  in  place, 
begin  laying  the  moulding.  Run  it  in  a 
straight  line,  on  the  wall  against  the  ceiling 
wherever  possible,  mitering  the  joints  neatly. 
Whenever  it  is  necessary  to  change  the  run 
from  the  ceiling  to  the  wall  and  a  miter  cannot 
be  made,  the  wires  should  be  protected  in 


WIRING  THE  HOUSE  181 

passing  from  one  slot  to  the  other  by  being 
enclosed  in  non-metallic  flexible  conduit, 
called  circular  loom. 

In  running  wooden  moulding,  avoid  brick 
walls  liable  to  sweat  or  draw  dampness;  keep 
away  from  places  where  the  heat  of  a  stove 
might  destroy  the  rubber  insulation  of  the 
wires;  do  not  pass  nearer  than  six  inches  to 
water  pipes  when  possible — and  when  it  is 
necessary  to  pass  nearer  than  this,  the  wooden 
moulding  should  pass  above  the  pipe,  not 
below  it,  with  at  least  an  inch  of  air  space 
intervening,  thus  avoiding  dampness  from 
sweating  of  pipes. 


WALL  SWITCH 
Snap  switch  connections 

Places  where  chandeliers  or  wall  bracket 
lamps  are  to  be  installed  permanently  are 
fitted  with  wooden  terminal  blocks,  which  fit 


182         ELECTRICITY  FOR  THE  FARM 

over  the  moulding  and  flush  with  the  plaster. 
These,  after  holes  have  been  bored  in  them 
for  the  wires,  and  the  wires  drawn  through, 
should  be  screwed  firmly  to  the  wall  or  ceiling, 
always  choosing  a  joist  or  beam  for  support. 
Then  a  crow's-foot,  or  tripod  of  iron,  tapped 
and  threaded  for  iron  pipe,  is  screwed  to  the 
terminal  block.  The  iron  pipe  of  the  chan- 
delier or  wall  bracket  is  then  screwed  home 
in  this  crow's-foot. 

Do  not  begin  stringing  wires  until  all  the 
moulding  of  the  circuit  has  been  laid.  Then 
thread  the  wires  through  the  wall  or  floor 
.tubes  and  lay  them  in  their  respective  slots. 
If  trouble  be  found  making  them  stay  in 
place  before  the  capping  is  put  on,  small  tacks 
may  be  driven  into  the  moulding  beside  them 
to  hold  them.  When  a  terminal  block  is 
reached,  a  loop  is  made  of  each  wire,  through 
the  hole  cut  in  the  block,  if  the  circuit  is  to 
continue  in  the  same  direction.  If  it  is  to  end 
there,  the  two  wires  are  drawn  through  taut, 
and  cut  off  at  a  length  of  5  or  6  inches.  These 
end  wires,  or  loops,  are  then  scraped  bare  and 


WIRING  THE  HOUSE 


183 


spliced  to  the  two  wires  coming  out  of  the 
chandelier  or  wall  bracket.    This  joint  is  then 


PO&PQ&WBLEOZRD 
3-  BRANCH  BLOCK 
CC~  CEILING 
D  -FLOOR  BOX 
EE~  PORCELAIN  TUBES 
FFFF-  WALL 


Detail  of  wooden  moulding 


soldered  and  covered  with  tape,  and  the  shell 
of  the  chandelier  is  screwed  into  place,  covering 
the  joint. 


184         ELECTRICITY  FOR  THE  FARM 

If  the  moulding  is  run  along  the  walls  flush 
with  the  ceiling,  as  is  usual,  a  branch  is  made 
for  a  wall  light,  or  wall  tap,  by  means  of  a 
porcelain  "T,"  or  branch -block,  which  pro- 
vides the  means  for  running  the  circuit  at 
right  angles  to  itself  without  letting  the  wires 
come  in  contact  with  each  other  where  they 
cross.  Separable  current  taps  should  be  in- 
stalled in  handy  places  on  all  circuits,  so  that 
small  heating  devices  may  be  used  without 
removing  the  lamps  from  their  sockets.  The 
two  wires  are  bared  for  half  an  inch  where 
they  run  through  these  current  taps,  and  are 
fastened  by  means  of  brass  screws. 

* '  Multiple ' '  Connections 

All  electric  devices  for  this  installation — 
lamps,  irons,  vacuum  cleaners,  motors — must 
be  connected  across  the  circuit — that  is, 
bridged,  from  one  wire  to  the  other.  This  is 
called  multiple,  or  shunt  connection.  There 
is  only  one  exception  to  it,  in  wiring  the  house. 
That  one  exception  is  installing  a  wall  switch, 
the  ordinary  snap  switch.  Since  this  wrall 


WIRING  THE  HOUSE  185 

switch,  is,  in  effect,  merely  an  instrument, 
which  opens  or  closes  a  circuit,  it  should  be 
connected  to  only  one  wire,  which  is  cut  to 
provide  two  ends  for  the  screw  connections 
in  the  switch.  When  a  moulding  branch  is  run 
down  from  the  ceiling  to  some  convenient 
spot  for  a  snap  switch  (with  which  to  turn  the 
lights  of  a  room  on  or  off),  a  porcelain  "T"  is 
not  used.  All  that  is  necessary  to  do  is  to  loop 
the  bottom  wire  of  the  circuit  down  through 
the  branch  moulding,  and  connect  it  to  the 
switch  at  a  terminal  block,  or  porcelain  base. 
In  wiring  lamp  fixtures,  No.  14  rubber- 
covered  wire  will  usually  prove  too  large.  For 
this  purpose,  No.  18  may  be  used,  with  one 
lamp  to  each  loop.  Hanging  lamps  may  not 
be  supported  by  electric  lamp  cord  itself, 
if  there  is  more  than  one  lamp  in  the  cluster, 
because  the  weight  is  apt  to  break  the  elec- 
trical connections.  In  such  a  case,  the  lamp 
should  be  supported  by  a  chain,  and  the 
twisted  cord  conveying  current  to  the  electric 
bulbs,  is  woven  in  the  links  of  the  chain.  For 
the  pantry,  kitchen,  woodshed,  barn,  etc.,  a 


186         ELECTRICITY  FOR  THE  FARM 

single  hanging  lamp  may  be  suspended  from  a 
fielding  rosette,  as  shown  in  the  cut,  provided 
a  single  knot  is  tied  inside  both  the  rosette  and 
the  lamp  socket,  to  make  it  secure.  This 


ZxAJ^P  .SOCKET 
TAKEZTJLPA&T 


Detail  of  simple  hanging  lamp  supported  by  rosette 


makes  a  very  cheap  fixture.  The  rosette  of 
porcelain  will  cost  15  cents;  the  lamp  socket 
20  cents,  and  the  lamp  cord  suspending  the 
lamp  and  carrying  the  current  will  cost  1J^ 
cents  a  foot;  while  a  tin  shade  will  cost  another 
15  cents. 


WIRING  THE  HOUSE  187 

Official  Inspection 

In  all  communities,  your  insurance  agent 
must  inspect  and  pass  your  wiring  before  you 
are  permitted  to  throw  the  main  switch  and 
turn  on  the  electricity.  Frequently  they  re- 
quire that  the  moulding  be  left  uncapped, 
until  they  have  inspected  it.  If  you  have 
more  than  660  watts  in  lamps  to  a  circuit;  if 
your  joints  are  not  soldered  and  well  taped; 
if  the  moulding  is  used  in  any  concealed  or 
damp  place,  the  agent  is  liable  to  condemn 
your  work  and  refuse  permission  to  turn  on 
the  electricity.  However  the  rules  are  so 
clearly  defined  that  it  is  difficult  to  go  wrong; 
and  a  farmer  who  does  his  own  wiring  and 
takes  pride  in  its  appearance  is  more  apt  to  be 
right  than  a  professional  electrician  who  is 
careless  at  his  task.  After  the  work  has  been 
passed,  tack  on  the  moulding  capping,  with 
brads,  and  paint  the  moulding  to  match  the 
woodwork. 

Wooden  moulding  wiring  is  perfectly  satis- 
factory if  properly  installed.  It  is  forbidden 


188         ELECTRICITY  FOR  THE  FARM 

in  many  large  cities,  because  of  the  liability 
of  careless  workmanship.  It  should  never 
be  installed  in  damp  places,  or  out  of  sight. 
If  the  work  is  well  done,  the  system  leaves 
nothing  to  be  desired;  and  it  has  the  additional 
advantage  of  being  cheap,  and  easily  done  by 
any  farmer  who  can  use  carpenter  tools. 
Farmers  with  moulding  machinery  can  make 
their  own  moulding.  The  code  prescribes  it 
shall  be  of  straight-grained  wood;  that  the 
raceways  for  the  wires  shall  be  separated  by 
a  tongue  of  wood  one-half  inch  wide;  and  that 
the  backing  shall  be  at  least  |  inch  thick. 
It  must  be  covered,  inside  and  out,  with  at 
least  two  coats  of  moisture-repellant  paint. 
It  can  be  had  ready-made  for  about  2  cents 
a  foot. 

Special  Heating  Circuits 

If  one  plans  using  electricity  for  heavy-duty 
stoves,  such  as  ranges  and  radiators,  it  is 
necessary  to  install  a  separate  heating  circuit. 
This  is  the  best  procedure  in  any  event,  even 
when  the  devices  are  all  small  and  suited  to 


WIRING  THE  HOUSE  189 

lamp  circuits.  The  wire  used  can  be  deter- 
mined by  referring  to  the  table  for  carrying 
capacity,  under  the  column  headed  "rubber- 
covered."  A  stove  or  range  drawing  40 
amperes,  would  require  a  No.  4  wire,  in 
moulding.  A  good  plan  is  to  run  the  heating 
circuit  through  the  basement,  attaching  it  to 
the  rafters  by  means  of  porcelain  knobs. 
Branches  can  then  be  run  up  through  the  floor 
to  places  where  outlets  are  desired.  Such  a 
branch  circuit  should  carry  fuses  suitable  to 
the  allowed  carrying  capacity  of  the  wire. 

Knob  and  Cleat  Wiring 

Knob  and  cleat  wiring,  such  as  is  used 
extensively  for  barns  and  out-buildings,  re- 
quires little  explanation.  The  wires  should 
not  be  closer  than  2^  inches  in  open  places, 
and  a  wider  space  is  better.  The  wires  should 
be  drawn  taut,  and  supported  by  cleats  or 
knobs  at  least  every  four  feet.  In  case  of 
branch  circuits,  one  wire  must  be  protected 
from  the  other  it  passes  by  means  of  a  porce- 
lain tube.  It  should  never  be  used  in  damp 


190        ELECTRICITY  FOR  THE  FARM 


places,  and  should  be  kept  clear  of  dust  and 
litter,  and  protected  from  abrasion. 

Knob  and  tube  wiring  is  frequently  used 
in  houses,  being  concealed  between  walls  or 


^   <JQL5T 


LKTH&.  PLASTER) 

Knob  and  cleat  wiring 


FLEXIBLE 

CONDUIT 


flooring.  In  this  case,  the  separate  wires  are 
stretched  on  adjoining  beams  or  rafters,  and 
porcelain  tubes  are  used,  in  passing  through 
cross  beams.  For  a  ceiling  or  wall  outlet,  a 
spliced  branch  is  passed  through  the  plaster 
by  means  of  porcelain  tubes  or  flexible  loom. 


WIRING  THE  HOUSE  191 

Wires  from  the  house  to  the  barn  should  be 
uniform  with  transmission  wires.  At  the 
point  of  entry  to  buildings,  they  must  be  at 
least  six  inches  apart,  and  must  take  the  form 
of  the  "  drop  loop  "  as  shown  in  the  illustration. 
A  double-pole  entrance  switch  must  be  pro- 
vided, opening  downward,  with  a  double-pole 
fuse.  In  passing  over  buildings  wires  must 
not  come  closer  than  7  feet  to  flat  roofs,  or  one 
foot  to  a  ridge  roof.  Feed-wires  for  electric 
motors  should  be  determined  from  the  table 
of  safe  carrying  capacities,  and  should  be  of 
liberal  size. 


CHAPTER  IX 
THE   ELECTRIC   PLANT   AT   WORK 

Direct-connected  generating  sets — Belt  drive — The 
switchboard — Governors  and  voltage  regulators — 
Methods  of  achieving  constant  pressure  at  all 
loads:  Over-compounding  the  dynamo;  A  system 
of  resistances;  (A  home-made  electric  radiator); 
Regulating  voltage  by  means  of  the  rheostat — 
Automatic  devices — Putting  the  plant  in  opera- 
tion. 

DYNAMOS  may  be  connected  to  water  wheels 
either  by  means  of  a  belt,  or  the  armature  may 
spin  on  the  same  shaft  as  the  water  wheel 
itself.  The  latter  is  by  far  the  more  desirable 
way,  as  it  eliminates  the  loss  of  power  through 
shafting  and  belting,  and  does  away  alto- 
gether with  the  belts  themselves  as  a  source 
of  trouble.  An  installation  with  the  water 
wheel  and  armature  on  the  same  shaft  is 
called  a  "direct-connected  set"  and  is  of 
almost  universal  use  in  large  power  plants. 

To  be  able  to  use  such  a  direct-connected 

192 


THE  ELECTRIC  PLANT  AT  WORK      193 

set,  the  dynamo  must  be  designed  to  develop 
its  full  voltage  when  run  at  a  speed  identical 
with  that  of  the  water  wheel.-  That  is,  if  the 
dynamo  is  wound  to  be  run  at  a  speed  of  800 
revolutions  per  minute,  it  must  be  driven  by  a 
water  wheel  which  runs  at  this  speed  and  can 
be  governed  within  narrow  limits.  Small  im- 
pulse wheels  running  under  great  heads  attain 
high  speed,  and  for  such  wheels  it  is  possible 
to  obtain  a  suitable  dynamo  at  low  cost. 
For  instance,  a  12-inch  impulse  wheel,  running 
under  a  200-foot  head  will  develop  6%  horse- 
power when  running  at  a  speed  of  875  revolu- 
tions per  minute.  A  dynamo  for  direct 
coupling  to  such  a  wheel  should  have  a  rated 
speed  within  5  per  cent  of  875  r.  p.  m.;  and, 
as  generators  of  this  speed  are  to  be  had  from 
the  stock  of  almost  all  manufacturers,  there 
would  be  no  extra  charge. 

When  it  comes  to  the  larger  wheels,  how- 
ever, of  the  impulse  type,  or  to  turbines 
operating  under  their  usual  head  the  ques- 
tion becomes  a  little  more  difficult.  In  such 
cases,  the  speed  of  the  water  wheel  will  vary 


194         ELECTRICITY  FOR  THE  FARM 

from  150  revolutions  per  minute,  to  400,  which 
is  slow  speed  for  a  small  dynamo.  As  a  general 
rule,  the  higher  the  speed  of  a  dynamo,  the 
lower  the  cost;  because,  to  lower  the  speed  for 
a  given  voltage,  it  is  necessary  either  to  in- 
crease the  number  of  conductors  on  the  arma- 
ture, or  to  increase  the  number  of  field  coils,  or 
both.  That  means  a  larger  machine,  and  a 
corresponding  increase  in  cost. 

In  practice,  in  large  plants,  with  alternating- 
current  machines  it  has  become  usual  to  mount 
the  field  magnets  on  the  shaft,  and  build  the 
armature  as  a  stationary  ring  in  whose  air 
space  the  field  coils  revolve.  This  simplifies 
the  construction  of  slow-speed,  large-output 
dynamos.  Such  a  machine,  however,  is  not 
to  be  had  for  the  modest  isolated  plant  of  the 
farmer  with  his  small  water-power. 

Dynamos  can  be  designed  for  almost  any 
waterwheel  speed,  and,  among  small  manufac- 
turers especially,  there  is  a  disposition  to  fur- 
nish these  special  machines  at  little  advance 
in  price  over  their  stock  machines.  Fre- 
quently it  is  merely  a  matter  of  changing  the 


Instantaneous  photograph  of  high-pressure  water  jet  being  queiiched 
by  buckets  of  a  tangential  wheel 


A  tangential  wheel,  and  a  dynamo  keyed  to  the  same  shaft — the 
ideal  method  for  generating  electricity.  The  centrifugal  governor 
is  included, on  the  same  base 


THE  ELECTRIC  PLANT  AT  WORK      195 

winding  on  a  stock  machine.  The  farmer  him- 
self, in  many  cases,  can  re-wind  an  old  dynamo 
to  fit  the  speed  requirements  of  a  direct- 
connected  drive  if  the  difference  is  not  too 
great.  All  that  would  be  necessary  to  effect 
this  change  would  be  to  get  the  necessary 
winding  data  from  the  manufacturer  himself, 
and  proceed  with  the  winding.  This  data 
would  give  the  gauge  of  wire  and  the  number 
of  turns  required  for  each  spool  of  the  field 
magnets ;  and  the  gauge  of  wire  and  number  of 
turns  required  for  each  slot  in  the  armature. 
The  average  boy  who  has  studied  electricity 
(and  there  is  something  about  electricity  that 
makes  it  closer  to  the  boy's  heart  than  his  pet 
dog)  could  do  this  work.  The  advantages  of 
direct  drive  are  so  many  that  it  should  be  used 
wherever  possible. 

When  direct  drive  cannot  be  had,  a  belt 
must  be  used,  either  from  a  main  shaft,  or  a 
countershaft.  The  belt  must  be  of  liberal 
size,  and  must  be  of  the  "endless"  variety — 
with  a  scarfed  joint.  Leather  belt  lacing, 
or  even  the  better  grades  of  wire  lacing,  un- 


196        ELECTRICITY  FOR  THE  FARM 

less  very  carefully  used,  will  prove  unsatis- 
factory. The  dynamo  feels  every  variation 
in  speed,  and  this  is  reflected  in  the  lights. 
There  is  nothing  quite  so  annoying  as  flicker- 
ing lights.  Usually  this  can  be  traced  to  the 
belt  connections.  Leather  lacing  forms  a 
knot  which  causes  the  lights  to  flicker  at 
each  revolution  of  the  belt.  The  endless 
belt  does  away  with  this  trouble.  Most 
dynamos  are  provided  with  sliding  bases, 
by  which  the  machine  can  be  moved  one 
way  or  another  a  few  inches,  to  take  up  slack 
in  the  belt.  To  take  advantage  of  this,  the 
belt  must  be  run  in  a  horizontal  line,  or  nearly 
so.  Vertical  belting  is  to  be  avoided. 

The  dynamo  is  mounted  on  a  wooden  base, 
in  a  dry  location  where  it  is  protected  from 
the  weather,  or  dampness  from  any  source. 
It  must  be  mounted  firmly,  to  prevent  vibra- 
tion when  running  up  to  speed;  and  the 
switchboard  should  occupy  a  place  within 
easy  reach.  Wires  running  from  the  dynamo 
to  the  switchboard  should  be  protected  from 
injury,  and  must  be  of  ample  size  to  carry 


THE  ELECTRIC  PLANT  AT  WORK      197 

the  full  current  of  the  machine  without  heat- 
ing. A  neat  way  is  to  carry  them  down 
through  the  flooring  through  porcelain  tubes, 
thence  to  a  point  where  they  can  be  brought 
up  at  the  back  of  the  switchboard.  If  there 
is  any  danger  of  injury  to  these  mains  they 
may  be  enclosed  in  iron  pipe.  Keep  the 
wires  out  of  sight  as  much  as  possible,  and 
make  all  connections  on  the  back  of  the 
switchboard. 

The  Sivitchboard 

The  switchboard  is  constructed  of  some 
fireproof  material,  preferably  slate  or  marble. 
When  the  cost  of  this  material  is  an  item  to 


AMMETER,      VOLTMETER 


1         TO  AHVHT  F1BCD 
CONNSCTEDXTCVNAfiO 


Connecting  switchboard  instruments 

consider,  build  a  substantial  wooden  frame 
for  your  switchboard.  You  can  then  screw 
asbestos  shingles  to  this  to  hold  the  various 


198         ELECTRICITY  FOR  THE  FARM 

instruments  and  with  a  little  care  such  a 
switchboard  can  be  made  to  look  business- 
like, and  it  is  fully  as  serviceable  as  the  more 
expensive  kind.  The  switchboard  instru- 
ments have  already  been  described  briefly. 
They  consist  of  a  voltmeter  (to  measure 
voltage) ;  an  ammeter  (to  measure  the  strength 
of  the  current  drawn,  in  amperes),  a  rheostat 
(to  regulate  the  voltage  of  the  machine  to 
suit  the  individual  requirements);  and  the 
usual  switches  and  fuses.  The  main  switch 
should  be  so  wired  that  when  open  it  will 
throw  all  the  current  off  the  line,  but  still 
leave  the  field  coils,  the  voltmeter,  and  the 
switchboard  lamp  in  circuit.  The  main- 
switch  fuses  should  have  a  capacity  about 
50  per  cent  in  excess  of  the  full  load  of  the 
dynamo.  If  the  machine  is  rated  for  50  am- 
peres, 75-ampere  fuses  should  be  installed. 
This  permits  throwing  on  an  overload  in  an 
emergency;  and  at  the  same  time  guards 
against  a  short  circuit.  If  the  capacity  of 
the  machine  is  under  30  amperes,  plug  fuses, 
costing  3  cents  each,  can  be  used.  If  it  is 


THE  ELECTRIC  PLANT  AT  WORK      199 


above  this  capacity,  cartridge  fuses,  costing 
a  little  more,  are  required.  A  supply  of  these 
fuses  should  be  kept  handy  at  all  times. 

Governors  and  Voltage  Regulators 

The  necessity  for  water  wheel  governors 
will  vary  with  conditions.  As  a  general  rule, 
it  may  be  said  that  reaction  turbines  working 
under  a  low  head  with  a  large  quantity  of 
water  do  not  require 
as  much  governing 
as  the  impulse  wheel, 
working  under  high 
heads  with  small 
quantities  of  water. 
When  governing  is 
necessary  at  all,  it  is 
because  the  prime 
mover  varies  in 
speed  from  no  load 
to  full  load.  Planning  one's  plant  with  a  lib- 
eral allowance  of  power — two  water  horse- 
power to  one  electrical  horsepower  is  lib- 
eral— reduces  the  necessity  of  governors  to  a 


A  centrifugal  governor 
(Courtesy  of  the  C.  P.  Bradway 
Company,  West  Stafford,  Conn.) 


200         ELECTRICITY  FOR  THE  FARM 

minimum.  As  an  instance  of  this,  the  plant 
described  in  some  detail  in  Chapters  One  and 
Six  of  this  volume,  runs  without  a  governor. 

However,  a  surplus  of  water-power  is  not 
usual.  Generally  plants  are  designed  within 
narrow  limits ;  and  then  the  need  of  a  governor 
becomes  immediately  apparent.  There  are 
many  designs  of  governors  on  the  market, 
the  cheapest  being  of  the  centrifugal  type, 
in  which  a  pair  of  w.iirling  balls  are  connected 
to  the  water  wheel  gate  by  means  of  gears, 
and  open  or  close  the  gate  as  the  speed  lowers 
or  rises. 

Constant  speed  is  necessary  because  voltage 
is  directly  dependent  on  speed.  If  the  speed 
falls  £5  per  cent,  the  voltage  falls  likewise; 
and  a  plant  with  the  voltage  varying  between 
such  limits  would  be  a  constant  source  of 
annoyance,  as  well  as  expense  for  burned- 
out  lamps. 

Since  constant  voltage  is  the  result  aimed  at 
by  the  use  of  a  governor,  the  same  result  can 
be  attained  in  other  ways,  several  of  which 
will  be  explained  here  briefly. 


THE  ELECTRIC  PLANT  AT  WORK      201 

Over-Compounding 

(1)  Over-compounding  the  dynamo.  This 
is  simple  and  cheap,  if  one 'buys  the  right 
dynamo  in  the  first  instance;  or  if  he  can  do 
the  over-compounding  himself,  by  the  method 
described  in  the  concluding  paragraphs  of 
Chapter  Seven.  If  it  is  found  that  the  speed 
of  the  water  wheel  drops  25  per  cent  between 
no  load  and  full  load,  a  dynamo  with  field 
coils  over-compounded  to  this  extent  would 
give  a  fairly  constant  regulation.  If  you  are 
buying  a  special  dynamo  for  direct  drive,  your 
manufacturer  can  supply  you  with  a  machine 
that  will  maintain  constant  voltage  under  the 
normal  variations  in  speed  of  your  wheel. 

A  System  of  Resistances 

(2)  Constant  load  systems.  This  system 
provides  that  the  dynamo  shall  be  delivering  a 
fixed  amount  of  current  at  all  times,  under 
which  circumstances  the  water  wheel  would 
not  require  regulation,  as  the  demands  on  it 
would  not  vary  from  minute  to  minute  or  hour 
to  hour. 


202        ELECTRICITY  FOR  THE  FARM 

This  system  is  very  simply  arranged.  It 
consists  of  having  a  set  of  "resistances"  to 
throw  into  the  circuit,  in  proportion  to  the 
amount  of  current  used. 

Let  us  say,  as  an  example,  that  a  50-ampere 
generator  is  used  at  a  pressure  of  110  volts; 
and  that  it  is  desirable  to  work  this  plant  at 
80  per  cent  load,  or  40  amperes  current  draft. 
When  all  the  lights  or  appliances  were  in  use, 
there  would  be  no  outside  "resistance"  in  the 
circuit.  When  none  of  the  lights  or  appliances 
were  in  use  (as  would  be  the  case  for  many 
hours  during  the  day)  it  would  be  necessary  to 
consume  this  amount  of  current  in  some  other 
way — to  waste  it.  A  resistance  permitting 
40  amperes  of  current  to  flow,  would  be  neces- 
sary. Of  what  size  should  this  resistance  be? 

The  answer  is  had  by  applying  Ohm's  Law, 
explained  in  Chapter  Five.  The  Law  in  this 
case,  would  be  read  R  =  |.  Therefore,  in  this 
case  R  =  -Vo°  =  2/4  ohms  resistance,  would  be 
required,  switched  across  the  mains,  to  keep 
the  dynamo  delivering  its  normal  load. 

The  cheapest  form  of  this  resistance  would 


THE  ELECTRIC  PLANT  AT  WORK      203 

be  iron  wire.  In  place  of  iron  wire,  German 
silver  wire  could  be  used.  German  silver  wire 
is  to  be  had  cheaply,  and  is  nianufactured  in 
two  grades,  18%  and  30%,  with  a  resistance 
respectively  18  and  30  times  that  of  copper 
for  the  same  gauge.  Nichrome  wire  has  a 
resistance  60  times  that  of  copper;  and 
manganin  wire  has  a  resistance  65  times  that 
of  copper,  of  the  same  gauge. 

First  figure  the  number  of  feet  of  copper  wire 
suitable  for  the  purpose.  Allowing  500  cir- 
cular mills  for  each  ampere,  the  gauge  of  the 
wire  should  be  40  x  500  =  20,000  circular 
mills,  or  approximately  No.  7  B.  &  S.  gauge. 
How  many  feet  of  No.  7  copper  wire  would 
give  a  resistance  of  2%  ohms?  Referring  to 
the  copper  wire  table,  we  find  that  it  requires 
2006.2  of  No.  7  wire  to  make  one  ohm.  Then 
2^4  ohms  would  require  5,517  feet. 

Since  30  per  cent  German  silver  wire  is 
approximately  30  times  the  resistance  of 
copper,  a  No.  7  German  silver  wire,  for  this 
purpose,  would  be  1/30  the  length  of  the 
copper  wire,  or  186  feet.  If  nichrome  wire 


204         ELECTRICITY  FOR  THE  FARM 

were  used,  it  would  be  l/60th  the  length  of 
copper  for  the  same  gauge,  or  93  feet.  This 
resistance  wire  can  be  wound  in  spirals  and 
made  to  occupy  a  very  small  space.  As  long 
as  it  is  connected  in  circuit,  the  energy  of  the 
dynamo  otherwise  consumed  as  light  would  be 
wasted  as  heat.  This  heat  could  be  utilized 
in  the  hot  water  boiler  or  stove  when  the  lights 
were  turned  off. 

In  actual  practice,  however,  the  resistance 
necessary  to  keep  the  dynamo  up  to  full  load 
permanently,  would  not  be  furnished  by  one 
set  of  resistance  coils.  Each  lamp  circuit 
would  have  a  set  of  resistance  coils  of  its  own. 
A  double-throw  switch  would  turn  off  the 
lamps  and  turn  on  the  resistance  coils,  or 
vice  versa. 

Let  us  say  a  lamp  circuit  consisted  of  6 
carbon  lamps,  of  16  candlepower  each.  It 
would  consume  6  x  J^  ampere,  or  3  amperes  of 
current,  and  interpose  a  resistance  of  36.6 
ohms — say  37  ohms.  Three  amperes  would 
require  a  wire  of  at  least  1,500  circular  mills  in 
area  for  safety.  This  corresponds  to  a  No.  18 


THE  ELECTRIC  PLANT  AT  WORK      205 

wire.  A  No.  18  copper  wire  interposes  a 
resistance  of  one  ohm,  for  each  156.5  feet 
length.  For  37  ohms,  5,790  feet  would  be 
required,  for  copper  wire,  which  of  course 
would  be  impractical.  Dividing  by  30  gives 
193  feet  for  30%  German  silver  wire;  and 
dividing  by  60  gives  96  feet  of  nichrome  wire 
of  the  same  gauge. 

It  is  simple  to  figure  each  circuit  in  this  way 
and  to  construct  resistance  units  for  each 
switch.  Since  the  resistance  units  develop 
considerable  heat,  they  must  be  enclosed  and 
protected. 

A  Home-made  Stove  or  Radiator 

While  we  are  on  the  subject  of  resistance  coils 
it  might  be  well  here  to  describe  how  to  make 
stoves  for  cooking,  and  radiators  for  heating 
the  house,  at  small  expense.  These  stoves 
consist  merely  of  resistances  which  turn  hot — 
a  dull  red — when  the  current  is  turned  on. 
Iron  wire,  German  silver  wire,  or  the  various 
trade  brands  of  resistance  wire,  of  which 
nichrome,  calido,  and  manganin  are  samples, 


206        ELECTRICITY  FOR  THE  FARM 

can  be  used.  In  buying  this  wire,  procure  the 
table  of  resistance  and  carrying  capacity  from 
the  manufacturers.  From  this  table  you  can 
make  your  own  radiators  to  keep  the  house 
warm  in  winter.  Iron  wire  has  the  disad- 
vantage of  oxidizing  when  heated  to  redness, 
so  that  it  goes  to  pieces  after  prolonged  use.  It 
is  cheap,  however,  and  much  used  for  resist- 
ance in  electrical  work. 

Let  us  say  we  wish  to  heat  a  bathroom,  a 
room  6x8,  and  8  feet  high — that  is  a  room 
containing  384  cubic  feet  of  air  space.  Allow- 
ing 2  watts  for  each  cubic  foot,  we  would  re- 
quire 768  watts  of  current,  or  practically  7 
amperes  at  110  volts.  What  resistance  would 
be  required  to  limit  the  current  to  this  amount? 
Apply  Ohm's  Law,  as  before,  and  we  have 
R  equals  E  divided  by  C,  or  R  equals  110 
divided  by  7,  which  is  15.7  ohms.  Forty-two 
feet  of  No.  20  German  silver  wire  would  emit 
this  amount  of  heat  and  limit  the  current  out- 
put to  7  amperes.  In  the  Far  West,  it  is  quite 
common,  in  the  outlying  district,  to  find  elec- 
tric radiators  made  out  of  iron  pipe  covered 


THE  ELECTRIC  PLANT  AT  WORK      207 

with  asbestos,  on  which  the  requisite  amount 
of  iron  wire  is  wound  and  made  secure.  This 
pipe  is  mounted  in  a  metal  frame.  Or  the 
frame  may  consist  of  two  pipes  containing 
heating  elements;  and  a  switch,  in  this  case,  is 
so  arranged  that  either  one  or  two  heating 
elements  may  be  used  at  one  time,  according 
to  the  weather.  An  ingenious  mechanic  can 
construct  such  a  radiator,  experimenting 
with  the  aid  of  an  ammeter  to  ascertain 
the  length  of  wire  required  for  any  given 
stove. 

Regulating  Voltage  at  Switchboards 

The  voltage  of  any  given  machine  may 
be  regulated,  within  wide  limits,  by  means 
of  the  field  rheostat  on  the  switchboard. 

A  dynamo  with  a  rated  speed  of  1,500 
revolutions  per  minute,  for  110  volts,  will 
actually  attain  this  voltage  at  as  low  as  1,200 
r.  p.  m.  if  all  the  regulating  resistance  be  cut 
out.  You  can  test  this  fact  with  your  own 
machine  by  cutting  out  the  resistance  from 
the  shunt  field  entirely,  and  starting  the 


208         ELECTRICITY  FOR  THE  FARM 

machine  slowly,  increasing  its  speed  gradu- 
ally, until  the  voltmeter  needle  registers  110 
volts.  Then  measure  the  speed.  It  will  be 
far  below  the  rated  speed  of  your  machine. 

If,  on  the  other  hand,  the  speed  of  such  a 
machine  runs  up  to  2,500  or  over — that  is, 
an  excess  of  67% — the  voltage  would  rise 
proportionally,  unless  extra  resistance  was 
cut  in.  By  cutting  in  such  resistance — by 
the  simple  expedient  of  turning  the  rheostat 
handle  on  the  switchboard, — the  field  coils 
are  so  weakened  that  the  voltage  is  kept  at 
the  desired  point  in  spite  of  the  excessive  speed 
of  the  machine.  Excessive  speeds  are  to  be 
avoided,  as  a  rule,  because  of  mechanical 
strain.  But  within  a  wide  range,  the  switch- 
board rheostat  can  be  used  for  voltage  regu- 
lation. 

As  it  would  be  a  source  of  continual  annoy- 
ance to  have  to  run  to  the  switchboard  every 
time  the  load  of  the  machine  was  varied 
greatly  this  plan  would  not  be  practical  for 
the  isolated  plant,  unless  the  rheostat  could 
be  installed, — with  a  voltmeter — in  one's 


THE  ELECTRIC  PLANT  AT  WORK      209 

kitchen.  This  could  be  done  simply  by  run- 
ning a  small  third  wire  from  the  switchboard 
to  the  house.  Then,  when  the  lights  became 
dim  from  excessive  load,  a  turn  of  the  handle 
would  bring  them  back  to  the  proper  voltage; 
and  when  they  flared  up  and  burned  too 
bright,  a  turn  of  the  handle  in  the  opposite 
direction  would  remedy  matters.  By  this 
simple  arrangement,  any  member  of  the 
family  could  attend  to  voltage  regulation  with 
a  minimum  of  bother. 

Automatic  Devices 

There  are  several  automatic  devices  for 
voltage  regulation  at  the  switchboard  on  the 
market.  These  consist  usually  of  vibrator 
magnets  or  solenoids,  in  which  the  strength 
of  the  current,  varying  with  different  speeds, 
reacts  in  such  a  way  as  to  regulate  field  re- 
sistance. Such  voltage  regulators  can  be  had 
for  $40  or  less,  and  are  thoroughly  reliable. 

To  sum  up  the  discussion  of  governors  and 
voltage  regulators:  If  you  can  allow  a  liberal 


210         ELECTRICITY  FOR  THE  FARM 

proportion  of  water-power,  and  avoid  crowding 
your  dynamo,  the  chances  are  you  will  not 
need  a  governor  for  the  ordinary  reaction 
turbine  wheel.  Start  your  plant,  and  let 
it  run  for  a  few  days  or  a  few  weeks  without  a 
governor,  or  regulator.  Then  if  you  find 
the  operation  is  unsatisfactory,  decide  for 
yourself  which  of  the  above  systems  is  best 
adapted  for  your  conditions.  Economy  as 
well  as  convenience  will  affect  your  decision. 
The  plant  which  is  most  nearly  automatic  is 
the  best;  but  by  taking  a  little  trouble  and 
giving  extra  attention,  a  great  many  dollars 
may  be  saved  in  extras. 

Starting  the  Dynamo 

You  are  now  ready  to  put  your  plant  in 
operation.  Your  dynamo  has  been  mounted 
on  a  wooden  foundation,  and  belted  to  the 
countershaft,  by  means  of  an  endless 
belt. 

See  that  the  oil  cups  are  filled.  Then  throw 
off  the  main  switch  and  the  field  switch  at 
the  switchboard;  open  the  water  gate  slowly, 


THE  ELECTRIC  PLANT  AT  WORK      211 

and  occasionally  test  the  speed  of  the  dynamo. 
When  it  comes  up  to  rated  speed,  say  1,500 
per  minute,  let  it  run  for  a 'few  minutes,  to 
be  sure  everything  is  all  right. 

Having  assured  yourself  that  the  mechanical 
details  are  all  right,  now  look  at  the  volt- 
meter. It  is  probably  indicating  a  few  volts 
pressure,  from  4  to  8  or  10  perhaps.  This 
pressure  is  due  to  the  residual  magnetism  in 
the  field  cores,  as  the  field  coils  are  not  yet 
connected.  If  by  any  chance,  the  needle 
does  not  register,  or  is  now  back  of  0,  try 
changing  about  the  connections  or  the  volt- 
meter on  the  back  of  the  switchboard. 

Now  snap  on  the  field  switch.  Instantly 
the  needle  will  begin  to  move  forward,  though 
slowly;  and  it  will  stop.  Turn  the  rheostat 
handle  gradually;  as  you  advance  it,  the  volt- 
meter needle  will  advance.  Finally  you  will 
come  to  a  point  where  the  needle  will  indicate 
110  volts. 

If  you  have  designed  your  transmission 
line  for  a  drop  of  5  volts  at  half -load,  advance 
the  rheostat  handle  still  further,  until  the 


ELECTRICITY  FOR  THE  FARM 

needle  points  to  115  volts.  Let  the  machine 
run  this  way  for  some  time.  When  assured 
all  is  right,  throw  on  the  main  switch,  and 
turn  on  the  light  at  the  switchboard.  Then 
go  to  the  house  and  gradually  turn  on  lights. 
Come  back  and  inspect  the  dynamo  as  the 
load  increases.  It  should  not  run  hot,  nor 
even  very  warm,  up  to  full  load.  Its  brushes 
should  not  spark,  though  a  little  sparking 
will  do  no  harm. 

Your  plant  is  now  ready  to  deliver  current 
up  to  the  capacity  of  its  fuses.  See  that  it 
does  not  lack  good  lubricating  oil,  and  do 
not  let  its  commutator  get  dirty.  The  com- 
mutator should  assume  a  glossy  chocolate 
brown  color.  If  it  becomes  dirty,  or  the 
brushes  spark  badly,  hold  a  piece  of  fine 
sandpaper  against  it.  Never  use  emery  paper ! 
If,  after  years  of  service,  it  becomes  roughened 
by  wear,  have  it  turned  down  in  a  lathe. 
Occasionally,  every  few  weeks,  say,  take  the 
brushes  out  and  clean  them  with  a  cloth. 
They  will  wear  out  in  the  course  of  time  and 
can  be  replaced  for  a  few  cents  each.  The 


THE  ELECTRIC  PLANT  AT  WORK      213 

bearings    may   need   replacing   after   several 
years'  continuous  use. 

Otherwise  your  electric  plaiit  will  take  care 
of  itself.  Keep  it  up  to  speed,  and  keep  it 
clean  and  well  oiled.  Never  shut  it  down 
unless  you  have  to.  In  practice,  dynamos 
run  week  after  week,  year  after  year,  without 
stopping.  This  one,  so  long  as  you  keep  it 
running  true  to  form,  will  deliver  light,  heat 
and  power  to  you  for  nothing,  which  your 
city  cousin  pays  for  at  the  rate  of  10  cents  a 
kilowatt-hour. 


PART  HI 

GASOLINE  ENGINES,  WINDMILLS, 
ETC.    THE  STORAGE  BATTERIES 


CHAPTER  X 

GASOLINE   ENGINE   PLANTS 

The  standard  voltage  set — two-cycle  and  four-cycle 
gasoline  engines — Horsepower,  and  fuel  consump- 
tion— Efficiency  of  small  engines  and  generators — 
Cost  of  operating  a  one-kilowatt  plant. 

ELECTRICITY  is  of  so  much  value  in  farm 
operations,  as  well  as  in  the  farm  house,  that 
the  farmer  who  is  not  fortunate  enough  to 
possess  water-power  of  his  own,  or  to  live 
in  a  community  where  a  cooperative  hydro- 
electric plant  may  be  established,  should 
not  deny  himself  its  many  conveniences. 
In  place  of  the  water  wheel  to  turn  the  dy- 
namo, there  is  the  gasoline  engine  (or  other 
forms  of  internal  combustion  engine  using 
oil,  gas,  or  alcohol  as  fuel);  in  many  districts 
where  steam  engines  are  used  for  logging  or 
other  operations,  electricity  may  be  generated 
as  a  by-product;  and  almost  any  windmill 
capable  of  pumping  water  can  be  made  to 

217 


218         ELECTRICITY  FOR  THE  FARM 

generate  enough  electricity  for  lighting  the 
farm  house  at  small  expense. 

The  great  advantage  of  water-power  is  that 
the  expense  of  maintenance — once  the  plant 
is  installed — is  practically  nothing.  This  ad- 
vantage is  offset  in  some  measure  by  the  fact 
that  other  forms  of  power,  gas,  steam,  or 
windmills,  are  already  installed,  in  many 
instances  and  that  their  judicious  use  in 
generating  electricity  does  not  impair  their 
usefulness  for  the  other  farm  operations  for 
which  they  were  originally  purchased.  In 
recent  years  gasoline  engines  have  come  into 
general  use  on  farms  as  a  cheap  dependable 
source  of  power  for  all  operations;  and  wind- 
mills date  from  the  earliest  times.  They 
may  be  installed  and  maintained  cheaply, 
solely  for  generating  electricity,  if  desired. 
Steam  engines,  however,  require  so  much  care 
and  expert  attention  that  their  use  for  farm 
electric  plants  is  not  to  be  advised,  except 
under  conditions  where  a  small  portion  of 
their  power  can  be  used  to  make  electricity  as 
a  by-product. 


GASOLINE  ENGINE  PLANTS  219 

There  are  two  types  of  gasoline  engine 
electric  plants  suitable  for  the  farm,  in  general 
use: 

First:  THE  STANDARD  VOLTAGE  SET,  in 
which  the  engine  and  dynamo  are  mounted  on 
one  base,  and  the  engine  is  kept  running  when 
current  is  required  for  any  purpose.  These 
sets  are  usually  of  the  110-volt  type,  and  all 
standard  appliances,  such  as  irons,  toasters, 
motors,  etc.,  may  be  used  in  connection  with 
them.  Since  the  electricity  is  drawn  directly 
from  the  dynamo  itself,  without  a  storage 
battery,  it  is  necessary  that  these  engines  be 
efficient  and  governed  as  to  speed  within  a 
five  per  cent  variation  from  no  load  to  full 
load. 

Second:  STORAGE  BATTERY  SETS,  in  which 
the  dynamo  is  run  only  a  few  hours  each 
week,  and  the  electricity  thus  generated  is 
"stored"  by  chemical  means,  in  storage 
batteries,  for  use  when  required.  Since,  in  this 
case,  the  current  is  drawn  from  the  battery, 
instead  of  the  dynamo,  when  used  for  lighting 
or  other  purposes,  it  is  not  necessary  that  a 


220         ELECTRICITY  FOR  THE  FARM 

special  type  of  engine  be  used  to  insure  con- 
stant speed. 

The  Standard  Voltage  Set 

In  response  to  a  general  demand,  the  first 
type  (the  direct-connected  standard  voltage 
set)  has  been  developed  to  a  high  state  of 
efficiency  recently,  and  is  to  be  had  in  a  great 
variety  of  sizes  (ranging  from  one-quarter 
kilowatt  to  25  kilowatts  and  over)  from  many 
manufacturers . 

The  principle  of  the  gasoline  engine  as 
motive  power  is  so  familiar  to  the  average 
farmer  that  it  needs  but  a  brief  description 
here.  Gasoline  or  other  fuel  (oil,  gas,  or 
alcohol)  is  transformed  into  vapor,  mixed  with 
air  in  correct  proportions,  and  drawn  into  the 
engine  cylinder  and  there  exploded  by  means 
of  a  properly-timed  electric  spark. 

Internal  combustion  engines  are  of  two 
general  types — four-cycle  and  two-cycle.  The 
former  is  by  far  the  more  common.  In  a  four- 
cycle engine  the  piston  must  travel  twice  up 
and  down  in  each  cylinder,  to  deliver  one 


GASOLINE  ENGINE  PLANTS 

power  stroke.  This  results  in  one  power  im- 
pulse in  each  cylinder  every  two  revolutions 
of  the  crank  shaft.  On  its  first  down  stroke, 
the  piston  sucks  in  gas.  On  its  first  up  stroke, 
it  compresses  the  gas.  At  the  height  of  this 
stroke,  the  gas  is  exploded  by  means  of  the 
electric  spark  and  the  piston  is  driven  down, 
on  its  power  stroke.  The  fourth  stroke  is 
called  the  scavening  stroke,  and  expels  the 
burned  gas.  This  completes  the  cycle. 

A  one-cylinder  engine  of  the  ordinary  four- 
cycle type  has  one  power  stroke  for  every  two 
revolutions  of  the  fly  wheel.  A  two-cylinder 
engine  has  one  power  stroke  for  one  revolution 
of  the  fly  wheel;  and  a  four-cylinder  engine 
has  two  power  strokes  to  each  revolution. 
The  greater  the  number  of  cylinders,  the  more 
even  the  flow  of  power.  In  automobiles  six 
cylinders  are  common,  and  in  the  last  year  or 
two,  eight-cylinder  engines  began  appearing 
on  the  market  in  large  numbers.  A  twelve- 
cylinder  engine  is  the  prospect  for  the  im- 
mediate future. 

Since  the  dynamo  that  is  to  supply  electric 


222         ELECTRICITY  FOR  THE  FARM 

current  direct  to  lamps  requires  a  steady  flow 
of  power,  the  single-cylinder  gas  or  gasoline 
engine  of  the  four-cycle  type  is  not  satisfactory 
as  a  rule.  The  lights  will  flicker  with  every 
other  revolution  of  the  fly  wheel.  This  would 
be  of  no  importance  if  the  current  was  being 
used  to  charge  a  storage  battery — and  right 
here  lies  the  reason  why  a  cheaper  engine  may 
be  used  in  connection  with  a  storage  battery 
than  when  the  dynamo  supplies  the  current 
direct  for  lighting. 

A  two-cylinder  engine  is  more  even  in  its 
flow  of  power  and  a  four-cylinder  engine  still 
better.  For  this  reason,  standard  voltage 
generating  sets  without  battery  are  usually 
of  two  or  four  cylinders  when  of  the  four-cycle 
type.  When  a  single-cylinder  engine  is  used, 
it  should  be  of  the  two-cycle  type.  In  the 
two-cycle  engine,  there  is  one  power  stroke  to 
each  up-and-down  journey  of  the  piston. 
This  effect  is  produced  by  having  inlet  and 
exhaust  ports  in  the  crank  case,  so  arranged 
that,  when  the  piston  arrives  at  the  bottom  of 
the  power  stroke,  the  waste  gases  are  pushed 


GASOLINE  ENGINE  PLANTS  223 

out,  and  fresh  gas  drawn  in  before  the  up 
stroke  begins. 

For  direct  lighting,  the  engine  must  be 
governed  so  as  not  to  vary  more  than  five  per 
cent  in  speed  between  no  load  and  full  load. 
There  are  many  makes  on  the  market  which 
advertise  a  speed  variation  of  three  per  cent 
under  normal  loads.  Governors  are  usually 
of  the  centrifugal  ball  type,  integral  with  the 
fly  wheel,  regulating  the  amount  of  gas  and 
air  supplied  to  the  cylinders  in  accordance 
with  the  speed.  Thus,  if  such  an  engine  began 
to  slow  down  because  of  increase  in  load,  the 
centrifugal  balls  would  come  closer  together, 
and  open  the  throttle,  thus  supplying  more 
gas  and  air  and  increasing  the  speed.  If  the 
speed  became  excessive,  due  to  sudden  shut- 
ting off  of  lights,  the  centrifugal  balls  would 
fly  farther  apart,  and  the  throttle  would  close 
until  the  speed  was  again  adjusted  to  the  load. 

These  direct-connected  standard  voltage 
sets  are  as  a  rule  fitted  with  the  110- volt, 
direct  current,  compound  type  of  dynamo, 
the  duplicate  in  every  respect  of  the  machine 


224         ELECTRICITY  FOR  THE  FARM 

described  in  previous  chapters  for  water- 
power  plants.  They  are  practically  automatic 
in  operation  and  will  run  for  hours  without 
attention,  except  as  to  oil  and  gasoline  supply. 
They  may  be  installed  in  the  woodshed  or 
cellar  without  annoyance  due  to  noise  or 
vibration.  It  is  necessary  to  start  them,  of 
course,  when  light  or  power  is  desired,  and  to 
stop  them  when  no  current  is  being  drawn. 
There  have  appeared  several  makes  on  the 
market  in  which  starting  and  stopping  are 
automatic.  Storage  batteries  are  used  in 
connection  with  these  latter  plants  for  starting 
the  engine.  When  a  light  is  turned  on,  or 
current  is  drawn  for  any  purpose,  an  auto- 
matic switch  turns  the  dynamo  into  a  motor, 
and  it  starts  the  engine  by  means  of  the  current 
stored  in  the  battery.  Instantly  the  engine  has 
come  up  to  speed,  the  motor  becomes  a  dy- 
namo again  and  begins  to  deliver  current. 
When  the  last  light  is  turned  off,  the  engine 
stops  automatically. 

Since  the  installation  of  a  direct-connected 
standard  voltage  plant  of  this  type  is  similar 


GASOLINE  ENGINE  PLANTS  225 

in  every  respect,  except  as  to  motive  power, 
to  the  hydro-electric  plant,  its  cost,  with  this 
single  exception,  is  the  same.  The  same  lamps, 
wire,  and  devices  are  used. 

With  gasoline  power,  the  cost  of  the  engine 
offsets  the  cost  of  the  water  wheel.  The  engine 
is  more  expensive  than  the  ordinary  gasoline 
engine;  but  even  this  item  of  cost  is  offset  by 
the  cost  of  labor  and  materials  used  in  in- 
stalling a  water  wheel. 

The  expense  of  maintenance  is  limited  to 
gasoline  and  oil.  Depreciation  enters  in  both 
cases;  and  though  it  may  be  more  rapid  with  a 
gasoline  engine  than  a  water  wheel,  that  item 
will  not  be  considered  here.  The  cost  of 
lubricating  oil  is  inconsiderable.  It  will  re- 
quire, when  operated  at  from  one-half  load 
to  full  load,  approximately  one  pint  of  gasoline 
to  each  horsepower  hour.  When  operated 
at  less  than  half-load,  its  efficiency  lowers. 
Thus,  for  a  quarter-load,  an  average  engine  of 
this  type  may  require  three  pints  of  gasoline 
for  each  horsepower  hour.  For  this  reason  it  is 
well,  in  installing  such  a  plant,  to  have  it  of 


226         ELECTRICITY  FOR  THE  FARM 

such  size  that  it  will  be  operating  on  at  least 
three-fourths  load  under  normal  draft  of  cur- 
rent. Norman  H.  Schneider,  in  his  book 
"Low  Voltage  Electric  Lighting,"  gives  the 
following  table  of  proportions  between  the 
engine  and  dynamo: 


Actual  watts 

Actual  Horsepower        1 

Nearest  e 

150 

.5 

] 

225 

.7 

j 

300 

.86 

1 

450 

1.12 

1 

600 

1.5 

1] 

750 

1.7 

11 

1000 

2.3 

2; 

2000 

4.5 

5 

4000 

9.0 

10 

This  table  is  figured  for  an  efficiency  of  only 
40  per  cent  for  the  smaller  generators,  and 
60  per  cent  for  the  larger.  In  machines  from( 
5  to  25  kilowatts,  the  efficiency  will  run  con- 
siderably higher. 

To  determine  the  expense  of  operating  a  one- 
kilowatt  gasoline  generator  set  of  this  type,  as 
to  gasoline  consumption,  we  can  assume  at 
full  load  that  the  gasoline  engine  is  delivering 
horsepower,  and  consuming,  let  us  say, 
f  gasoline  for  each  horsepower  hour 


GASOLINE  ENGINE  PLANTS  227 

(to  make  allowance  for  lower  efficiency  in 
small  engines).  That  would  be  3.125  pints  of 
gasoline  per  hour.  Allowing  a  ten  per  cent 
loss  of  current  in  wiring,  we  have  900  watts  of 
electricity  to  use,  for  this  expenditure  of 
gasoline.  This  would  light  900  -r-  25  =  36 
lamps  of  25  watts  each,  a  liberal  allowance  for 
house  and  barn,  and  permitting  the  use  of 
small  cooking  devices  and  other  conveniences 
when  part  of  the  lights  were  not  in  use.  With 
gasoline  selling  at  12  cents  a  gallon,  the  use  of 
this  plant  for  an  hour  at  full  capacity  would 
cost  $0.047.  Your  city  cousin  pays  9  cents 
for  the  same  current  on  a  basis  of  10  cents  per 
kilowatt-hour;  and  in  smaller  towns  where 
the  rate  is  15  cents,  he  would  pay  13*/£  cents. 
Running  this  plant  at  only  half-load — that 
is,  using  only  18  lights,  or  their  equivalent — 
would  reduce  the  price  to  about  3  cents  an 
hour — since  the  efficiency  decreases  with 
smaller  load.  It  is  customary  to  figure  an 
average  of  3^2  hours  a  day  throughout  the 
year,  for  all  lights.  On  this  basis  the  cost  of 
gasoline  for  this  one-kilowatt  plant  would  be 


228         ELECTRICITY  FOR  THE  FARM 


cents  a  day  for  full  load,  and  approx- 
imately 10%  cents  a  day  for  half-load.  This 
is  extremely  favorable,  as  compared  with  the 
cost  of  electric  current  in  our  cities  and  towns, 
at  the  commercial  rate,  especially  when  one 
considers  that  light  and  power  are  to  be  had  at 
any  place  or  at  any  time  on  the  farm  simply 
by  starting  the  engine.  A  smaller  plant, 
operating  at  less  cost  for  fuel,  would  furnish 
ample  light  for  most  farms;  but  it  is  well  to 
remember  in  this  connection  plants  smaller 
than  one  kilowatt  are  practical  for  light  only, 
since  electric  irons,  toasters,  etc.,  draw  from 
400  to  660  watts  each.  Obviously  a  plant  of 
300  watts  capacity  would  not  permit  the  use  of 
these  instruments,  although  it  would  furnish 
10  or  12  lamps  of  25  watts  each. 


CHAPTER  XI 

THE    STORAGE   BATTERY 

What  a  storage  battery  does — The  lead  battery  and 
the  Edison  battery — Economy  of  tungsten  lamps 
for  storage  batteries — The  low-voltage  battery 
for  electric  light — How  to  figure  the  capacity  of  a 
battery — Table  of  light  requirements  for  a  farm 
house — Watt-hours  and  lamp-hours — The  cost 
of  storage  battery  current — How  to  charge  a  stor- 
age battery — Care  of  storage  batteries. 

FOR  the  man  who  has  a  small  supply  of 
water  to  run  a  water  wheel  a  few  hours  at  a 
time,  or  who  wishes  to  store  electricity  while 
he  is  doing  routine  jobs  with  a  gasoline  engine 
or  other  source  of  power,  the  storage  battery 
solves  the  problem.  The  storage  battery  may 
be  likened  to  a  tank  of  water  which  is  drawn 
on  when  water  is  needed,  and  which  must  be 
re-filled  when  empty.  A  storage  battery,  or 
accumulator  is  a  device  in  which  a  chemical 
action  is  set  up  when  an  electric  current  is 
passed  through  it.  This  is  called  charging. 

229 


230         ELECTRICITY  FOR  THE  FARM 

When  such  a  battery  is  charged,  it  has  the 
property  of  giving  off  an  electric  current  by 
means  of  a  reversed  chemical  action  when  a 
circuit  is  provided,  through  a  lamp  or  other 
connection.  This  reversed  action  is  called 
discharging.  Such  a  battery  will  discharge 
nearly  as  much  current  as  is  required  orig- 
inally to  bring  about  the  first  chemical  action. 

There  are  two  common  types  of  storage 
battery — the  lead  accumulator,  made  up  of 
lead  plates  (alternately  positive  and  negative) ; 
and  the  two-metal  accumulator,  of  which  the 
Edison  battery  is  a  representative,  made  up  of 
alternate  plates  of  iron  and  nickel.  In  the 
lead  accumulator,  the  "positive"  plate  may  be 
recognized  by  its  brown  color  when  charging, 
while  the  "negative"  plate  is  usually  light 
gray,  or  leaden  in  color.  The  action  of  the 
charging  current  is  to  form  oxides  of  lead  in  the 
plates;  the  action  of  the  discharging  current 
is  to  reduce  the  oxides  to  metallic  lead  again. 
This  process  can  be  repeated  over  and  over 
again  during  the  life  of  the  battery. 

Because  of  the  cost  of  the  batteries  them- 


THE  STORAGE  BATTERY      231 

selves,  it  is  possible  (from  the  viewpoint  of  the 
farmer  and  the  size  of  bis  pocketbook)  to  store 
only  a  relatively  small  amount  of  electric  cur- 
rent. For  this  reason,  the  storage  battery  was 
little  used  for  private  plants,  where  expense  is 
a  considerable  item,  up  to  a  few  years  ago. 
Carbon  lamps  require  from  3^  to  4  watts  for 
each  candlepower  of  light  they  give  out;  and  a 
lead  battery  capable  of  storing  enough  elec- 
tricity to  supply  the  average  farm  house  with 
light  by  means  of  carbon  lamps  for  three  or 
four  days  at  a  time  without  recharging,  proved 
too  costly  for  private  use. 

The  Tungsten  Lamp 

With  the  advent  of  the  new  tungsten  lamp, 
however,  reducing  the  current  requirements 
for  light  by  two-thirds,  the  storage  battery 
immediately  came  into  its  own,  and  is  now  of 
general  use. 

Since  incandescent  lamps  were  first  invented 
scientists  have  been  trying  to  find  some 
metal  of  high  fusion  to  use  in  place  of  the 
carbon  filament  of  the  ordinary  lamp.  The 


ELECTRICITY  FOR  THE  FARM 

higher  the  fusing  point  of  this  filament  of  wire, 
the  more  economical  would  be  the  light. 
Edison  sought,  thirty  years  ago,  for  just  the 
qualities  now  found  in  tungsten  metal.  Tung- 
sten metal  was  first  used  for  incandescent 
lamps  in  the  form  of  a  paste,  squirted  into  the 
shape  of  a  thread.  This  proved  too  fragile. 
Later  investigators  devised  means  of  drawing 
tungsten  into  wire;  and  it  is  tungsten  wire  that 
is  now  used  so  generally  in  lighting.  A  tung- 
sten lamp  has  an  average  efficiency  of  lj^ 
watts  per  candlepower,  compared  with  3^  to 
4  watts  of  the  old-style  carbon  lamp.  In 
larger  sizes  the  efficiency  is  as  low  as  .9  watt 
per  candlepower;  and  only  recently  it  has  been 
found  that  if  inert  nitrogen  gas  is  used  in  the 
glass  bulb,  instead  of  using  a  high  vacuum  as 
is  the  general  practice,  the  efficiency  of  the 
lamp  becomes  still  higher,  approaching  .5 
watt  for  each  candlepower  in  large  lamps. 
This  new  nitrogen  lamp  is  not  yet  being 
manufactured  in  small  domestic  sizes,  though 
it  will  undoubtedly  be  put  on  the  market 
in  those  sizes  in  the  near  future. 


THE  STORAGE  BATTERY 


233 


The  tungsten  lamp,  requiring  only  one-third 
as  much  electric  current  as  the  carbon  lamp, 
for  the  same  amount  of  light,  reduces  the  size 
(and  the  cost)  of  the  storage  battery  in  the 
same  degree,  thus  bringing  the  storage  battery 
within  the  means 
of  the  farmer. 
Some  idea  of  the 
power  that  may 
be  put  into  a 
small  storage 
battery  is  to  be 
had  from  the 
fact  that  a  stor- 
age battery  of 
only  6  volts  pres- 

sure,  SUch    as    is     The  Fairbanks  Morse  oil  engine  storage 


Used 


n      Se 


lf- 


battery  set 

starters  on  automobiles,  will  turn  a  motor 
and  crank  a  heavy  six-cylinder  engine;  or  it 
will  run  the  automobile,  without  gasoline,  for 
a  mile  or  more  with  its  own  accumulated  store 
of  electric  current. 


234         ELECTRICITY  FOR  THE  FARM 

The  Low  Voltage  Battery 

The  30-volt  storage  battery  has  become 
standard  for  small  lighting  plants,  since  the 
introduction  of  the  tungsten  lamp.  Although 
the  voltage  of  each  separate  cell  of  this  bat- 
tery registers  2.5  volts  when  fully  charged,  it 
falls  to  approximately  2  volts  per  cell  imme- 
diately discharging  begins.  For  this  reason,  it 
is  customary  to  figure  the  working  pressure  of 
each  cell  at  2  volts.  This  means  that  a  30-volt 
battery  should  consist  of  at  least  15  cells. 
Since,  however,  the  voltage  falls  below  2  for 
each  cell,  as  discharging  proceeds,  it  is  usual 
to  include  one  additional  cell  for  regulating 
purposes.  Thus,  the  ordinary  30-volt  storage 
battery  consists  of  16  cells,  the  last  cell  in  the 
line  remaining  idle  until  the  lamps  begin  to 
dim,  when  it  is  switched  in  by  means  of  a 
simple  arrangement  of  connections.  This 
maintains  a  uniform  pressure  of  30  volts  from 
the  beginning  to  the  end  of  the  charge,  at  the 
lamp  socket. 

We  saw  in  earlier  chapters  that  the  110- volt 


THE  STORAGE  BATTERY      235 

current  is  the  most  satisfactory,  under  all 
conditions,  where  the  current  is  to  be  used  for 
heating  and  small  power,  as  well  as  light.  But 
a  storage  battery  of  110  volts  would  require  at 
least  55  cells,  which  would  make  it  too  expen- 
sive for  ordinary  farm  use.  As  a  30-volt  cur- 
rent is  just  as  satisfactory  for  electric  light, 
this  type  has  become  established,  in  connec- 
tion with  the  battery,  and  it  is  used  for  electric 
lighting  only,  as  a  general  rule. 

Batteries  are  rated  first,  as  to  voltage; 
second,  as  to  their  capacity  in  ampere  hours — 
that  is,  the  number  of  amperes  that  may  be 
drawn  from  them  in  a  given  number  of  hours. 
Thus,  a  battery  rated  at  60  ampere  hours 
would  give  60  amperes,  at  30  volts  pressure, 
for  one  hour;  30  amperes  for  2  hours;  15  am- 
peres for  4  hours;  7J^  amperes  for  8  hours; 
3^4  amperes  for  16  hours;  etc.,  etc.  In  prac- 
tice, a  battery  should  not  be  discharged  faster 
than  its  8-hour  rate.  Thus,  a  60-ampere 
hour  battery  should  not  be  drawn  on  at  a 
greater  rate  than  7^2  amperes  per  hour. 

This  8-hour  rate  also  determines  the  rate 


236         ELECTRICITY  FOR  THE  FARM 

at  which  a  battery  should  be  re-charged, 
once  it  is  exhausted.  Thus,  this  battery 
should  be  charged  at  the  rate  of  7J^  amperes 
for  8  hours,  with  another  hour  added  to 
make  up  for  losses  that  are  bound  to  occur. 
A  battery  of  120-ampere  hour  capacity  should 
be  charged  for  8  or  9  hours  at  the  rate  of 
120-5-8,  or  15  amperes,  etc. 

To  determine  the  size  of  battery  necessary 
for  any  particular  instance,  it  is  necessary 
first  to  decide  on  the  number  of  lamps  required, 
and  their  capacity.  Thirty- volt  lamps  are 
to  be  had  in  the  market  in  sizes  of  10,  15  and 
20  watts;  they  yield  respectively  8,  12,  and 
16  candlepower  each.  Of  these  the  20- watt 
lamp  is  the  most  satisfactory  for  the  living 
rooms;  lamps  of  10  or  15  watts  may  be  used 
for  the  halls,  the  bathroom  and  the  bedrooms. 
At  30  volts  pressure  these  lamps  would  require 
a  current  of  the  following  density  in  amperes: 

Candle 

Power  30-volt  lamp  Amperes 

8 10  watts 0.33 

12 15  watts 0.50 

16.  .  ..20  watts..  .  0.67 


THE  STORAGE  BATTERY      237 

Let  us  assume,  as  an  example,  that  Farmer 
Brown  will  use  20-watt  lamps  in  his  kitchen, 
dining  room,  and  sitting  room;  and  10-watt 
lamps  in  the  halls,  bathroom,  and  bedrooms. 
His  requirements  may  be  figured  either  in 
lamp  hours  or  in  watt-hours.  Since  he  is  using 
two  sizes  of  lamps,  it  will  be  simpler  to  figure 
his  requirements  in  watt-hours.  Thus: 

Number  Size  of  Hours  Watt- 
Room                     of  lamps  lamps  burned  hours 

Kitchen 1  20  4  80 

Dining  room 2  20  2  80 

Sitting  room 3                        20  4  240 

(3)  Bedrooms 1  (each)             10  1  30 

Bathroom 1                         10  2  20 

(2)  Halls 1  (each)            10  4  80 

Pantry 1                         10  1  10 

Cellar.  .                       .1                        10  1  10 


Total 550 

Since  amperes  equal  watts  divided  by  volts, 
the  number  of  ampere  hours  required  in  this 
case  each  night  would  be  550-7-30  =  18.3 
ampere  hours;  or  approximately  4J^  amperes 
per  hour  for  4  hours. 

Say  it  is  convenient  to  charge  this  battery 
every  fourth  day.  This  would  require  a  bat- 


238         ELECTRICITY  FOR  THE  FARM 

tery  of  4  x  18.3  ampere  hours,  or  73.2  ampere 
hours.  The  nearest  size  on  the  market  is  the 
80-ampere  hour  battery,  which  would  be  the 
one  to  use  for  this  installation. 

To  charge  this  battery  would  require  a 
dynamo  capable  of  delivering  10  amperes  of 
current  for  9  hours.  The  generator  should  be 
of  45  volts  pressure  (allowing  2J/2  volts  in 
the  generator  for  each  2  volts  of  battery) 
and  the  capacity  of  the  generator  would  there- 
fore be  450  watts.  This  would  require  a  1J^ 
horsepower  gasoline  engine.  At  1^  pints 
of  gasoline  for  each  horsepower,  nine  hours 
work  of  this  engine  would  consume  14  pints 
of  gasoline — or  say  16  pints,  or  two  gallons. 
At  12  cents  a  gallon  for  gasoline,  lighting 
your  house  with  this  battery  would  cost  24 
cents  for  four  days,  or  6  cents  a  day.  Your 
city  cousin,  using  commercial  current,  would 
pay  5  j/2  cents  a  day  for  the  same  amount  of 
current  at  10  cents  a  kilowatt-hour;  or  8% 
cents  at  a  15-cent  rate.  If  the  battery  is 
charged  by  the  farm  gasoline  engine  at  the 
same  time  it  is  doing  its  other  work,  the  cost 


THE  STORAGE  BATTERY      239 

would  be  still  less,  as  the  extra  gasoline  re- 
quired would  be  small. 

This  figure  does  not  take  into  account  de- 
preciation of  battery  and  engine.  The  average 
farmer  is  too  apt  to  overlook  this  factor  in 
figuring  the  cost  of  machinery  of  all  kinds, 
and  for  that  reason  is  unprepared  when  the 
time  comes  to  replace  worn-out  machinery. 
The  dynamo  and  switchboard  should  last  a 
lifetime  with  ordinary  care,  so  there  is  no  de- 
preciation charge  against  them.  The  storage 
battery,  a  30-volt,  80-ampere  hour  installation, 
should  not  cost  in  excess  of  $100;  and,  if  it  is 
necessary  to  buy  a  gasoline  engine,  a  1J4 
horsepower  engine  can  be  had  for  $50  or  less 
according  to  the  type.  Storage  batteries  of 
the  lead  type  are  sold  under  a  two-years' 
guarantee — which  does  not  mean  that  their 
life  is  limited  to  that  length  of  time.  With 
good  care  they  may  last  as  long  as  10  years; 
with  poor  care  it  may  be  necessary  to  throw 
them  away  at  the  end  of  a  year.  The  engine 
should  be  serviceable  for  at  least  10  years, 
with  ordinary  replacements;  and  the  storage 


240         ELECTRICITY  FOR  THE  FARM 

battery  may  last  from  6  to  10  years,  with  oc- 
casional renewal  of  parts.  If  it  were  necessary 
to  duplicate  both  at  the  end  of  ten  years,  this 
would  make  a  carrying  charge  of  $1.25  a 
month  for  depreciation,  which  must  be  added 
to  the  cost  of  light. 

Figuring  by  Lamp  Hours 

If  all  the  lamps  are  to  be  of  the  same  size — 
either  ten,  fifteen,  or  twenty  watts,  the  light 
requirements  of  a  farm  house  can  be  figured 
readily  by  lamp  hours.  In  that  event,  the 
foregoing  table  would  read  as  follows: 

Lamp  hours 

Kitchen,  1  lamp,  4  hours 4 

Sitting  room,  3  lamps,  4  hours  each 12 

Dining   room,  2  lamps,  2  hours  each 4 

Bedrooms,  3  lamps,  1  hour  each 3 

Halls,  2  lamps,  4  hours  each 8 

Bathroom,  1  lamp,  2  hours 2 

Pantry  and  cellar,  2  lamps,  1  hour  each 2 

To  determine  the  ampere  hours  from  this 
table,  multiply  the  total  number  of  lamp 
hours  by  the  current  in  amperes  required  for 
each  lamp.  As  10,  15,  and  20- watt  tungsten 
lamps  require  .33,  .50  and  .67  amperes,  re- 


THE  STORAGE  BATTERY      241 

spectively  at  30  volts  pressure,  the  above 
requirements  in  ampere  hours  would  be  12, 
17j^,  or  24  ampere  hours,  according  to  the 
size  of  lamp  chosen.  This  gives  the  average 
current  consumption  for  one  night.  If  it  is 
desired  to  charge  the  battery  twice  a  week 
on  the  average,  multiply  the  number  of  lamp 
hours  by  4,  to  get  the  size  of  battery  required. 

The  foregoing  illustration  is  not  intended 
to  indicate  average  light  requirements  for 
farms,  but  is  given  merely  to  show  how  a 
farmer  may  figure  his  own  requirements. 
In  some  instances,  it  will  be  necessary  to 
install  a  battery  of  120  or  more  ampere  hours, 
whereas  a  battery  of  40  or  60  ampere  hours 
would  be  quite  serviceable  in  other  instances. 
It  all  depends  on  how  much  light  you  wish 
to  use  and  are  willing  to  pay  for,  because 
with  a  storage  battery  the  cost  of  electric  light 
is  directly  in  proportion  to  the  number  of 
lights  used. 

As  a  general  rule,  a  larger  generator  and 
engine  are  required  for  a  larger  battery — 
although  it  is  possible  to  charge  a  large  bat- 


242         ELECTRICITY  FOR  THE  FARM 

tery  with  a  small  generator  and  engine  by 
taking  more  time  for  the  operation. 

How  to  Charge  a  Storage  Battery 

Direct  current  only  can  be  used  for  charging 
storage  batteries.  In  the  rare  instance  of 
alternating  current  only  being  available,  it 
must  be  converted  into  direct  current  by  any 
one  of  the  many  mechanical,  chemical,  or 
electrical  devices  on  the  market — that  is,  the 
alternating  current  must  be  straightened  out, 
to  flow  always  in  one  direction. 

A  shunt- wound  dynamo  must  be  used;  else, 
when  the  voltage  of  the  battery  rises  too  high, 
it  may  "back  up"  and  turn  the  dynamo  as  a 
motor,  causing  considerable  damage.  If  a 
compound  dynamo  is  already  installed,  or  if  it 
is  desired  to  use  such  a  machine  for  charging 
storage  batteries,  it  can  be  done  simply  by 
disconnecting  the  series  windings  on  the  field 
coils,  thus  turning  the  machine  into  a  shunt 
dynamo. 

The  voltage  of  the  dynamo  should  be 
approximately  50  per  cent  above  the  working 


THE  STORAGE  BATTERY      243 

pressure  of  the  battery.  For  this  reason  45- 
volt  machines  are  usually  used  for  30  or  32- 
volt  batteries.  Higher  voltages  may  be  used, 
if  convenient.  Thus  a  110-volt  dynamo  may 
be  used  to  charge  a  single  2-volt  cell  if  neces- 
sary, although  it  is  not  advisable. 

Direction  of  Current 

Electricity  flows  from  the  positive  to  the 
negative  terminal.  A  charging  current  must 
be  so  connected  that  the  negative  wire  of  the 
dynamo  is  always  connected  to  the  negative 
terminal  of  the  battery,  and  the  positive  wire 
to  the  positive  terminal.  As  the  polarity  is 
always  marked  on  the  battery,  there  is  little 
danger  of  making  a  mistake  in  this  particular. 

When  the  storage  battery  is  charged,  and 
one  begins  to  use  its  accumulation  of  energy, 
the  current  comes  out  in  the  opposite  direction 
from  which  it  entered  in  charging.  In  this 
respect,  a  storage  battery  is  like  a  clock  spring, 
which  is  wound  up  in  one  direction,  and  un- 
winds itself  in  the  other.  With  all  storage 
battery  outfits,  an  ammeter  (or  current  meas- 


244         ELECTRICITY  FOR  THE  FARM 

ure)  is  supplied  with  zero  at  the  center.  When 
the  battery  is  being  charged,  the  indicating 
needle  points  in  one  direction  in  proportion 
to  the  strength  of  the  current  flowing  in; 
and  when  the  battery  is  being  discharged,  the 
needle  points  in  the  opposite  direction,  in 
proportion  to  the  strength  of  the  current  flow- 
ing out. 

Sometimes  one  is  at  loss,  in  setting  about  to 
connect  a  battery  and  generator,  to  know 
which  is  the  positive  and  which  the  negative 
wire  of  the  generator.  A  very  simple  test  is  as 
follows: 

Start  the  generator  and  bring  it  up  to 
speed.  Connect  some  form  of  resistance  in 
"series"  with  the  mains.  A  lamp  in  an 
ordinary  lamp  socket  will  do  very  well  for  this 
resistance.  Dip  the  two  ends  of  the  wire  (one 
coming  from  the  generator,  the  other  through 
the  lamp)  into  a  cup  of  water,  in  which  a 
pinch  of  salt  is  dissolved.  Bring  them  almost 
together  and  hold  them  there.  Almost  in- 
stantly, one  wire  will  begin  to  turn  bright,  and 
give  off  bubbles.  The  wire  which  turns 


A  rough-and-ready  farm  electric  plant,  supplying  two  farms  with  light,  heat 
and  power;  and  a  Ward  Leonard-type  circuit- breaker  for  charging  storage 
batteries 


THE  STORAGE  BATTERY      245 

bright  and  gives  off  bubbles  is  the  negative 
wire.    The  other  is  the  positive. 

Care  of  Battery 

Since  specific  directions  are  furnished  with 
all  storage  batteries,  it  is  not  necessary  to  go 
into  the  details  of  their  care  here.  Storage 
battery  plants  are  usually  shipped  with  all 
connections  made,  or  plainly  indicated.  All 
that  is  necessary  is  to  fill  the  batteries  with  the 
acid  solution,  according  to  directions,  and 
start  the  engine.  If  the  engine  is  fitted  with  a 
governor,  and  the  switchboard  is  of  the  au- 
tomatic type,  all  the  care  necessary  in  charging 
is  to  start  the  engine.  In  fact,  many  makes 
utilize  the  dynamo  as  a  "self-starter"  for 
the  engine,  so  that  all  that  is  necessary 
to  start  charging  is  to  throw  a  switch  which 
starts  the  engine.  When  the  battery  is  fully 
charged,  the  engine  is  stopped  automati- 
cally. 

The  "electrolyte"  or  solution  in  which  the 
plates  of  the  lead  battery  are  immersed,  is 
sulphuric  acid,  diluted  with  water  hi  the 


246         ELECTRICITY  FOR  THE  FARM 

proportion  of  one  part  of  acid  to  five  of  water, 
by  volume. 

The  specific  gravity  of  ordinary  commercial 
sulphuric  acid  is  1.835.  Since  its  strength  is 
apt  to  vary,  however,  it  is  best  to  mix  the 
electrolyte  with  the  aid  of  the  hydrometer 
furnished  with  the  battery.  The  hydrometer 
is  a  sealed  glass  tube,  with  a  graduated  scale 
somewhat  resembling  a  thermometer.  The 
height  at  which  it  floats  in  any  given  solution 
depends  on  the  density  of  the  solution.  It 
should  indicate  approximately  1.15  for  a  stor- 
age battery  electrolyte  before  charging.  It 
should  not  be  over  1.15 — or  1,150  if  your 
hydrometer  reads  in  thousandths. 

Only  pure  water  should  be  used.  Distilled 
water  is  the  best,  but  fresh  clean  rain  water  is 
permissible.  Never  under  any  circumstances 
use  hydrant  water,  as  it  contains  impurities 
which  will  injure  the  battery,  probably  put 
it  out  of  commission  before  its  first  charge. 

Pour  the  acid  into  the  water.  Never  under 
any  circumstances  pour  the  water  into  the 
acid,  else  an  explosion  may  occur  from  the 


THE  STORAGE  BATTERY      247 

heat  developed.  Mix  the  electrolyte  in  a 
stone  crock,  or  glass  container,  stirring  with  a 
glass  rod,  and  testing  from  time  to  time  with  a 
hydrometer.  Let  it  stand  until  cool  and  then 
pour  it  into  the  battery  jars,  filling  them  to 
y%  inch  above  the  top  of  the  plates. 

Then  begin  charging.  The  first  charge  will 
probably  take  a  longer  time  than  subsequent 
charges.  If  the  installation  is  of  the  auto- 
matic type,  all  that  is  necessary  is  to  start  the 
engine.  If  it  is  not  of  the  automatic  type, 
proceed  as  follows: 

First  be  sure  all  connections  are  right. 
Then  start  the  engine  and  bring  the  dynamo 
up  to  its  rated  speed.  Adjust  the  voltage 
to  the  pressure  specified.  Then  throw  the 
switch  connecting  generator  to  battery.  Watch 
the  ammeter.  It  should  register  in  amperes, 
one-eighth  of  the  ampere-hour  capacity  of  the 
battery,  as  already  explained.  If  it  registers 
too  high,  reduce  the  voltage  of  the  generator 
slightly,  by  means  of  the  field  rheostat  con- 
nected to  the  generator.  This  will  also  reduce 
the  amperes  flowing.  If  too  low,  raise  the 


248         ELECTRICITY  FOR  THE  FARM 

voltage  until  the  amperes  register  correctly. 
Continue  the  charging  operation  until  the 
cells  begin  to  give  off  gas  freely;  or  until  the 
specific  gravity  of  the  electrolyte,  measured 
by  the  hydrometer,  stands  at  1.24.  Your 
battery  is  now  fully  charged.  Throw  the 
switch  over  to  the  service  line,  and  your 
accumulator  is  ready  to  furnish  light  if  you 
turn  on  your  lamps. 

Occasionally  add  distilled  water  to  the  cells, 
to  make  up  for  evaporation.  It  is  seldom 
necessary  to  add  acid,  as  this  does  not  evap- 
orate. If  the  battery  is  kept  fully  charged,  it 
will  not  freeze  even  when  the  thermometer  is 
well  below  zero. 

A  storage  battery  should  be  installed  as  near 
the  house  as  possible — in  the  house,  if  possible. 
Since  its  current  capacity  is  small,  transmis- 
sion losses  must  be  reduced  to  a  minimum. 

In  wiring  the  house  for  storage  battery  serv- 
ice, the  same  rules  apply  as  with  standard 
voltage.  Not  more  than  6  amperes  should  be 
used  on  any  single  branch  circuit.  With  low 
voltage  batteries  (from  12  volts  to  32  volts)  it 


THE  STORAGE  BATTERY      249 

is  well  to  use  No.  10  or  No.  12  B.  &  S.  gauge 
rubber-covered  wire,  instead  of  the  usual 
No.  14  used  with  standard  voltage.  The  extra 
expense  will  be  only  a  few  cents  for  each  cir- 
cuit, and  precious  volts  will  be  saved  in  dis- 
tribution of  the  current. 


CHAPTER  XII 

BATTERY    CHARGING   DEVICES 

The  automatic  plant  most  desirable — How  an  auto- 
mobile lighting  and  starting  system  works — How 
the  same  results  can  be  achieved  in  house  lighting, 
by  means  of  automatic  devices — Plants  without 
automatic  regulation — Care  necessary — The  use 
of  heating  devices  on  storage  battery  current — 
Portable  batteries — An  electricity  "route" — Auto- 
mobile power  for  lighting  a  few  lamps. 

THE  water-power  electric  plants  described 
in  preceding  chapters  are  practically  auto- 
matic in  operation.  This  is  very  desirable, 
as  such  plants  require  the  minimum  of  care. 
It  is  possible  to  attain  this  same  end  with  a 
storage  battery  plant. 

Automatic  maintenance  approaches  a  high 
degree  of  perfection  in  the  electric  starting 
and  lighting  device  on  a  modern  automobile. 
In  this  case,  a  small  dynamo  geared  to  the 
main  shaft  is  running  whenever  the  engine 
is  running.  It  is  always  ready  to  "pump" 

250 


BATTERY  CHARGING  DEVICES        251 

electricity  into  the  storage  battery  when 
needed.  An  electric  magnet,  wound  in  a 
peculiar  manner,  automatically  cuts  off  the 
charging  current  from  the  dynamo,  when 
the  battery  is  "full;"  and  the  same  magnet, 
or  "regulator,"  permits  the  current  to  flow 
into  the  battery  when  needed.  The  principle 
is  the  same  as  in  the  familiar  plumbing  trap, 
which  constantly  maintains  a  given  level  of 
water  in  a  tank,  no  matter  how  much  water 
may  be  drawn  from  the  tank.  The  result, 
in  the  case  of  the  automobile  battery,  is  that 
the  battery  is  always  kept  fully  charged; 
for  no  sooner  does  the  "level"  of  electricity 
begin  to  drop  (when  used  for  starting  or 
lighting)  than  the  generator  begins  to  charge. 
This  is  very  desirable  in  more  ways  than  one. 
In  the  first  place,  the  energy  of  the  battery 
is  always  the  same;  and  in  the  second  place, 
the  mere  fact  that  the  battery  is  always  kept 
fully  charged  gives  it  a  long  life. 

The  same  result  can  be  achieved  in  storage 
battery  plants  for  house  lighting,  where  the 
source  of  power  is  a  gasoline  or  other  engine 


252         ELECTRICITY  FOR  THE  FARM 

engaged  normally  in  other  work.  Then  your 
electric  current  becomes  merely  a  by-product 
of  some  other  operation. 

Take  a  typical  instance  where  such  a  plant 
would  be  feasible:  Farmer  Brown  has  a  five 
horsepower  gasoline  engine — an  ordinary  farm 
engine  for  which  he  paid  probably  $75  or  $100. 
Electric  light  furnished  direct  from  such  an 
engine  would  be  intolerable  because  of  its 
constant  flickering.  This  five  horsepower 
engine  is  installed  in  the  milk  room  of  the 
dairy,  and  is  belted  to  a  countershaft.  This 
countershaft  is  belted  to  the  vacuum  pump 
for  the  milking  machine,  and  to  the  separator, 
and  to  a  water  pump,  any  one  of  which  may 
be  thrown  into  service  by  means  of  a  tight- 
and-loose  pulley.  This  countershaft  is  also 
belted  to  a  small  dynamo,  which  runs  when- 
ever the  engine  is  running.  The  milking 
machine,  the  separator,  and  the  water  pump 
require  that  the  gasoline  engine  be  run  on  the 
average  three  hours  each  day. 

The  dynamo  is  connected  by  wires  to  the 
house  storage  battery  through  a  properly 


BATTERY  CHARGING  DEVICES        253 

designed  switchboard.  The  "brains"  of  this 
switchboard  is  a  little  automatic  device  (called 
a  regulator  or  a  circuit  breaker),  which  opens 
and  shuts  according  to  the  amount  of  current 
stored  in  the  battery  and  the  strength  of  the 
current  from  the  generator.  When  the  bat- 
tery is  "full,"  this  regulator  is  "open"  and 
permits  no  current  to  flow.  Then  the  dynamo 
is  running  idle,  and  the  amount  of  power  it 
absorbs  from  the  gasoline  engine  is  negligible. 
When  the  "level"  of  electricity  in  the  battery 
falls,  due  to  drawing  current  for  light,  the 
regulator  is  "shut,"  that  is,  the  dynamo  and 
battery  are  connected,  and  current  flows  into 
the  battery. 

These  automatic  instruments  go  still  farther 
in  their  brainy  work.  They  do  not  permit 
the  dynamo  to  charge  the  battery  when  the 
voltage  falls  below  a  fixed  point,  due  to  the 
engine  slowing  down;  neither  do  they  permit 
the  dynamo  current  to  flow  when  the  voltage 
gets  too  high  due  to  sudden  speeding  up  of 
the  engine. 

Necessarily,  an  instrument  which  will  take 


254         ELECTRICITY  FOR  THE  FARM 

care  of  a  battery  in  this  way,  is  intricate  in 
construction.  That  is  not  an  argument  against 
it  however.  A  watch  is  intricate,  but  so  long 
as  we  continue  to  wind  it  at  stated  intervals, 
it  keeps  time.  So  with  this  storage  battery 
plant:  so  long  as  Farmer  Brown  starts  his 
engine  to  do  his  farm  chores  every  day,  his 
by-product  of  electricity  is  stored  auto- 
matically. 

Such  installations  are  not  expensive.  A 
storage  battery  capable  of  lighting  8  tungsten 
lamps,  of  16  candlepower  each,  continuously 
for  8  hours  (or  fewer  lamps  for  a  longer  time) ; 
a  switchboard  containing  all  the  required 
regulating  instruments;  and  a  dynamo  of 
suitable  size,  can  be  had  for  from  $250  to  $300. 
All  that  is  necessary  to  put  such  a  plant  in 
operation,  is  to  belt  the  dynamo  to  the  gaso- 
line engine  so  that  it  will  run  at  proper  speed; 
and  to  connect  the  wires  from  dynamo  to 
switchboard,  and  thence  to  the  house  service. 
The  dynamo  required  for  the  above  plant 
delivers  10  amperes  at  45  volts  pressure,  or 
10  x  45  =  450  watts.  A  gasoline,  gas,  or  oil 


BATTERY  CHARGING  DEVICES        255 


engine,  or  a  windmill  of  \Y^  horsepower 
furnishes  all  the  power  needed.  If  the  farmer 
uses  his  engine  daily,  or  every  other  day, 
for  other  purposes,  the  cost  of  power  will  be 
practically  negligible.  With  this  system  elec- 
tric lights  are  available  at  any  time  day  or 
night;  and  when  the  gasoline  engine  is  in  serv- 
ice daily  for  routine  farm  chores,  the  battery 
will  never  run  low. 

This  system  is  especially  desirable  where 
one  uses  a  windmill  for  power.  The  speed 
of  the  windmill  is  constantly  fluctuating,  so 
much  so  in  fact  that  it  could  not  be  used  for 
electric  light  without  a  storage  battery.  But 
when  equipped  with  a  regulator  on  the  switch- 
board which  permits  the  current  to  flow  only 
when  the  battery  needs  it,  and  then  only  when 
the  speed  of  the  windmill  is  correct,  the  prob- 
lem of  turning  wind  power  into  electric  light  is 
solved. 

If  the  farmer  does  not  desire  to  go  to  the 
additional  expense  of  automatic  regulation, 
there  are  cheaper  plants,  requiring  attention 


256         ELECTRICITY  FOR  THE  FARM 

for  charging.  These  plants  are  identical  with 
those  described  above,  except  they  have  no 
regulators.  With  these  plants,  when  the 
battery  runs  low  (as  is  indicated  by  dimming 
of  the  lights)  it  is  necessary  to  start  the  engine, 
bring  it  up  to  speed,  adjust  the  dynamo  volt- 
age to  the  proper  pressure,  and  throw  a  switch 
to  charge  the  battery.  For  such  plants 
it  is  customary  to  run  the  engine  to  charge 
the  battery  twice  a  week.  It  is  necessary  to 
run  the  engine  from  8  to  10  hours  to  fully 
charge  the  discharged  battery.  When  the 
battery  approaches  full  charge,  the  fact  is 
evidenced  by  so-called  "gassing"  or  giving 
off  of  bubbles.  Another  way  to  determine 
if  the  battery  is  fully  charged  is  by  means  of 
the  voltmeter,  as  the  volts  slowly  rise  to  the 
proper  point  during  the  process  of  charging. 
A  third  way,  and  probably  the  most  reliable 
is  by  the  use  of  the  hydrometer.  The  volt- 
age of  each  cell  when  fully  charged  should 
be  2.5;  it  should  never  be  discharged  below 
1.75  volts.  Many  storage  battery  electric 
light  plants  on  the  market  are  provided  with 


BATTERY  CHARGING  DEVICES        257 

a  simple  and  inexpensive  circuit  breaker, 
which  automatically  cuts  off  .the  current  and 
stops  the  engine  when  the  battery  is  charged. 
The  current  is  then  thrown  from  the  dynamo 
to  the  house  service  by  an  automatic  switch. 
If  such  a  circuit  breaker  is  not  included,  it  is 
necessary  to  throw  the  switch  by  hand  when 
charging  is  begun  or  ended. 

Since  the  principal  item  of  first  cost,  as 
well  as  depreciation,  in  a  storage  battery 
electric  light  plant  is  the  storage  battery  itself, 
the  smallest  battery  commensurate  with  needs 
is  selected.  Since  the  amount  of  current 
stored  by  these  batteries  is  relatively  small, 
electric  irons  and  heating  devices  such  as 
may  be  used  freely  on  a  direct-connected 
plant  without  a  battery,  are  rather  expensive 
luxuries.  For  instance,  an  electric  iron  draw- 
ing 400  watts  an  hour  while  in  use,  requires  as 
much  energy  as  20  tungsten  lamps  of  16 
candlepower  each  burning  for  the  same  length 
of  time.  Its  rate  of  current  consumption 
would  be  over  13  amperes,  at  30  volts; 
which  would  require  a  larger  battery  than 


258         ELECTRICITY  FOR  THE  FARM 

needed  for  light  in  the  average  farm 
home. 

The  use  to  which  electricity  from  a  storage 
battery  is  put,  however,  is  wholly  a  matter  of 
expense  involved;  and  if  one  is  willing  to  pay 
for  these  rather  expensive  luxuries,  there  is  no 
reason  why  he  should  not  have  them.  Heat- 
ing, in  any  form,  by  electricity,  requires  a 
large  amount  of  current  proportionally.  As  a 
matter  of  fact,  there  is  less  heat  to  be  had 
in  thermal  units  from  a  horsepower-hour  of 
electricity  than  from  three  ounces  of  coal. 
When  one  is  generating  current  from  water- 
power,  or  even  direct  from  gasoline  or  oil,  this 
is  not  an  argument  against  electric  heating 
devices.  But  it  becomes  a  very  serious  con- 
sideration when  one  is  installing  a  storage 
battery  as  the  source  of  current,  because  of  the 
high  initial  cost,  and  depreciation  of  such  a 
battery. 

Farmers  who  limit  the  use  of  their  storage 
battery  plants  to  lighting  will  get  the  best 
service. 


BATTERY  CHARGING  DEVICES        259 

Portable  Batteries 

Abroad  it  is  becoming  quite  common  for 
power  companies  to  deliver  storage  batteries 
fully  charged,  and  call  for  them  when  dis- 
charged. Without  a  stretch  of  the  imagina- 
tion, we  can  imagine  an  ingenious  farmer 
possessing  a  water-power  electric  plant  build- 
ing up  a  thriving  business  among  his  less 
fortunate  neighbors,  with  an  "electricity" 
route.  It  could  be  made  quite  as  paying  as  a 
milk  route. 

Many  communities  have 
water  or  steam  power  at  a 
distance  too  great  to  trans- 
mit 110- volt  current  by  wire 
economically;  and  because  of 
lack  of  expert  supervision, 
they  do  not  care  to  risk  using 

Gattery 

current  at  a  pressure  of  500     Connections  for charg- 

VoltS    Or    higher,    because    of    mg  storage  batteries  on 

110-volt  mains 

its  danger  to  human  life. 

In  such  a  case  it  would  be  quite  feasible  for 
families  to  wire  their  houses,  and  carry  their 


260         ELECTRICITY  FOR  THE  FARM 

batteries  to  the  generating  plant  two  or  three 
times  a  week  to  be  charged.  There  are  a  num- 
ber of  portable  batteries  on  the  market 
suitable  for  such  service,  at  voltages  ranging 
from  6  to  32  volts.  The  best  results  would  be 
obtained  by  having  two  batteries,  leaving  one 
to  be  charged  while  the  other  was  in  use;  and 
if  the  generating  station  was  located  at  the 
creamery  or  feed  mill,  where  the  farmer  calls 
regularly,  the  trouble  would  be  reduced  to  a 
minimum. 

Such  a  battery  would  necessarily  be  small, 
and  of  the  sealed  type,  similar  to  those  used 
in  automobiles.  It  could  be  used  merely  for 
reading  lamps — or  it  could  be  used  for  general 
lighting,  according  to  the  expense  the  farmer 
is  willing  to  incur  for  batteries. 

An  ordinary  storage  battery  used  in  auto- 
mobile ignition  and  lighting  systems  is  of 
the  6-volt,  60-ampere  type,  called  in  trade 
a  "6-60."  Lamps  can  be  had  for  these  bat- 
teries ranging  in  sizes  from  2  candlepower  to 
25  candlepower.  A  lamp  of  15  candlepower, 
drawing  2J/2  amperes,  is  used  for  automobile 


BATTERY  CHARGING  DEVICES        261 

headlights,  and,  as  any  one  knows  after  an 
experience  of  meeting  a  headlight  on  a  dark 
road,  they  give  a  great  deal  of  light.  A 
"6-60"  battery  keeps  one  of  these  lamps  run- 
ning for  24  hours,  or  two  lamps  running  12 
hours.  A  minimum  of  wiring  would  be  re- 
quired to  install  such  a  battery  for  the  reading 
lights  in  the  sitting  room,  and  for  a  hanging 
light  in  the  dining  room.  The  customary 
gates  for  charging  these  batteries  in  a  large 
city  is  10  cents;  but  in  a  country  plant  it  could 
be  made  less. 

To  charge  such  a  battery  on  a  110-volt 
direct  current,  it  is  necessary  to  install  some 
means  of  limiting  the  amount  of  current,  or  in 
other  words,  the  charging  rate.  This  charging 
rate,  for  8  hours  should  be,  as  we  have  seen, 
one-eighth  of  the  ampere-hour  capacity  of  the 
battery.  Thus  a  "6-60"  battery  would  re- 
quire a  71/2  ampere  current. 

Connecting  two  such  batteries  in  "series" 
(that  is,  the  negative  pole  of  one  battery  to 
the  positive  pole  of  the  second)  would  make  a 
12-volt  battery.  Ten  or  twelve  such  batteries 


262         ELECTRICITY  FOR  THE  FARM 

could  be  connected  in  "series,"  and  a  110- volt 
direct  current  generator  would  charge  them 
in  8  hours  at  a  7J^  ampere  rate. 

The  diagram  on  page  259  shows  the  connec- 
tions for  charging  on  a  110-volt  circuit. 

An  ordinary  16-candlepower  carbon  lamp 
is  of  220  ohms  resistance,  and  (by  Ohm's 
Law,  C  equals  E  divided  by  R)  permits  3^ 
ampere  of  current  to  flow.  By  connecting 
15  such  lamps  across  the  mains,  in  parallel, 
the  required  7^  amperes  of  current  would  be 
flowing  from  the  generator  through  the  lamps, 
and  back  again.  Connect  the  battery  in 
"series"  at  any  point  on  either  of  the  two 
mains,  between  the  lamps  and  the  generator, 
being  careful  to  connect  the  positive  end  to 
the  positive  pole  of  the  battery,  and  vice  versa. 

Lamps  are  the  cheapest  form  of  resistance; 
but  in  case  they  are  not  available,  any  other 
form  of  resistance  can  be  used.  Iron  wire 
wound  in  spirals  can  be  used,  or  any  of  the 
many  makes  of  special  resistance  wire  on  the 
market.  First  it  is  necessary  to  determine 
the  amount  of  resistance  required. 


BATTERY  CHARGING  DEVICES        263 

We  have  just  seen  that  the  charging  rate 
of  a  60-ampere  hour  battery  is  7j^  amperes. 
Applying  Ohm's  Law  here,  we  find  that  ohms 
resistance  equals  volts  divided  by  amperes, 
or  R  =  Vtf  =  14.67  ohms.  With  a  220-volt 
current,  the  ohms  resistance  required  in  series 
with  the  storage  battery  of  this  size  would  be 
29.33  ohms. 

Automobile  Power  for  Lighting 

There  are  many  ingenious  ways  by  which 
an  automobile  may  be  utilized  to  furnish 
electric  light  for  the  home.  The  simplest  is 
to  run  wires  direct  from  the  storage  battery 
of  the  self-starting  system,  to  the  house  or 
barn,  in  such  a  way  that  the  current  may  be 
used  for  reading  lamps  in  the  sitting  room. 
By  a  judicious  use  of  the  current  in  this  way, 
the  normal  operation  of  the  automobile  in 
the  daytime  will  keep  the  battery  charged 
for  use  of  the  night  lamps,  and  if  care  is  used, 
such  a  plan  should  not  affect  the  life  of  the 
battery.  Care  should  be  used  also,  in  this 
regard,  not  to  discharge  the  battery  too  low 


264         ELECTRICITY  FOR  THE  FARM 

to  prevent  its  utilizing  its  function  of  starting 
the  car  when  it  was  desired  to  use  the  car. 
However,  if  the  battery  were  discharged  be- 
low its  starting  capacity,  by  any  peradventure, 
the  car  could  be  started  by  the  old-fashioned 
cranking  method. 

Using  an  automobile  lighting  system  for 
house  lighting  implies  that  the  car  be  stored 
in  a  garage  near  the  house  or  barn;  as  this 
battery  is  too  low  in  voltage  to  permit  trans- 
mitting the  current  any  distance.  One  hun- 
dred feet,  with  liberal  sized  transmission 
wires  is  probably  the  limit. 

That  such  a  system  is  feasible  is  amply 
proved  by  an  occurrence  recently  reported 
in  the  daily  papers.  A  doctor  summoned 
to  a  remote  farm  house  found  that  an  imme- 
diate operation  was  necessary  to  save  the  pa- 
tient's life.  There  was  no  light  available, 
except  a  small  kerosene  lamp  which  was  worse 
than  nothing.  The  surgeon  took  a  headlight 
off  his  car,  strung  a  pair  of  wires  through  a 
window,  and  instantly  had  at  his  command 
a  light  of  the  necessary  intensity. 


BATTERY  CHARGING  DEVICES         265 

Another  manner  in  which  an  automobile 
engine  may  be  used  for  house  lighting  is  to 
let  it  serve  as  the  charging  powei  of  a  separate 
storage  battery.  The  engine  can  be  belted 
to  the  generator,  in  such  a  case,  by  means  of 
the  fly  wheel.  Or  a  form  of  friction  drive  can 
be  devised,  by  means  of  which  the  rear  wheels 
(jacked  up  off  the  floor)  may  supply  the  neces- 
sary motive  power.  In  such  a  case  it  would 
be  necessary  to  make  allowance  for  the  dif- 
ferential in  the  rear  axle,  so  that  the  power 
developed  by  the  engine  would  be  delivered  to 
the  friction  drive. 


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'"pHE  following  pages  contain   advertisements  of 
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BY  THE  SAME  AUTHOR 


The  Farmer  of  Tomorrow 

Cloth,  i2tno,  $1.50 

"A  crisp,  entertaining,  and  instructive  discussion 
of  the  conditions  which  have  brought  about  the  pres- 
ent agricultural  problem  in  America." — Countryside 

Magazine. 

"The  book  is  interestingly  written  and  full  of  many 
vital  discussions." — Annals  of  the  American  Academy 
of  Political  and  Social  Science. 

"A  popular  consideration  of  the  fundamental  fac- 
tors affecting  the  business  of  farming."— Pacific  Rural 
Press. 

"The  growing,  popular  question  of  farming  ana- 
lyzed from  all  angles,  with  many  helpful  suggestions." 
— Leslie's  Weekly. 

"Any  person  of  intelligence,  alive  to  the  present  and 
future  welfare  of  his  country  will  find  'The  Farmer  of 
Tomorrow/  a  book  of  absorbing  character." — Times- 
Star. 


THE  MACMILLAN  COMPANY 

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Cooperation  in  Agriculture 

BY  G.  HAROLD  POWELL 

Cloth,  i2mo,  $1.50 

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suggest  that  the  economic  advantages  of  cooperation 
may  frequently  be  quite  subordinate  to  the  general 
social  and  community  interests  which  are  fostered 
through  a  common  undertaking.  He  writes  with  the 
genuine  interest  of  a  man  having  experience  and  faith 
in  that  of  which  he  speaks." — Political  Science  Quar- 
terly. 

"A  volume  which  explains  in  a  lucid  way  the  fea- 
tures of  the  existing  system  and  the  measures  taken 
by  farmers  to  protect  their  interests." — Journal  of 
the  Royal  Statistical  Society. 

"Mr.  Powell  has  not  attempted  to  cover  the  entire 
field  of  agricultural  cooperation,  but  has  confined  him- 
self to  its  more  important  phases.  His  work  shows  a 
grasp  of  the  issues  involved  and  a  ripeness  of  conclu- 
sion that  conies  only  from  actual  contact  with  the 
practical  side  of  cooperation." — American  Economic 
Review. 

"The  book  is  decidedly  worth  while." — Farm  Life 
and  Agriculture. 

THE  MACMILLAN  COMPANY 

Publishers      64-66  Fifth  Avenue     New  York 


RURAL  SCIENCE   SERIES 

Edited  by  L.  H.  BAILEY 

Each  volume  illustrated.  Cloth,  12mo. 


A  series  of  practical  books  for  farmers  and  gardeners,  sold  as  a  set  or  separately. 
Each  one  is  the  work  of  a  competent  specialist,  and  is  suitable  for  consultation  alike 
by  the  amateur  or  professional  tiller  of  the  soil,  the  scientist  or  the  student.  Illus- 
trations of  marked  beauty  are  freely  used,  and  the  books  are  clearly  printed  and 
well  bound. 

ON  SELECTION  OF  LAND,  ETC. 

Isaac  P.  Roberts'  The  Farmstead $1  60 

T.  F.  Hunt's  How  to  Choose  a  Farm          1  75 

E.  S.  Cheyney  and  J.  P.  Wentling's  The  Farm  Woodlot       ...  1  50 
Glenn  W.  Herrick's  Insects  Injurious  to  the  Household        ...  1  75 

ON  TILLAGE,  ETC. 

F.  H.  King's  The  Soil 1  50 

Isaac  P.  Roberts'  The  Fertility  of  the  Land 1  50 

F.  H.  King's  Irrigation  and  Drainage 1  50 

Edward  B.  Voorhees'  Fertilizers 1  25 

Edward  B.  Voorhees'  Forage  Crops 1  50 

J.  A.  Widtsoe's  Dry  Farming 1  50 

L.  H.  Bailey's  Principles  of  Agriculture 1  25 

S.  M.  Tracy's  Forage  Crops  for  the  South 1  50 

ON  PLANT  DISEASES,  ETC. 

E.  C.  Lodeman's  The  Spraying  of  Plants 1  25 

ON  GARDEN-MAKING 

L.  H.  Bailey's  Garden-Making 1  50 

L.  H.  Bailey's  Vegetable-Gardening 1  50 

L.  H.  Bailey's  Forcing  Book 1  25 

L.  H.  Bailey's  Plant  Breeding ,  2  00 

P.  H.  Rolfs'  Subtropical  Vegetable-gardening 0  00 

ON  FRUIT-GROWING,   ETC. 

L.  H.  Bailey's  Nursery  Book 1  50 

L.  H.  Bailey's  Fruit-Growing  (New  Edition) 1  75 

L.  H.  Bailey's  The  Pruning  Book 1  50 

F.  W.  Card's  Bush  Fruits 1  50 

W.  Paddock  &  O.  B.  Whipple's  Fruit-Growing  in  Arid  Regions       .  1  50 

J.  E.  Coit's  Citrus  Fruits 2  00 

S.  W.  Fletcher's  The  Strawberry  in  North  America.    Preparing 

ON  THE  CARE  OF  LIVE  STOCK 

Nelson  S.  Mayo's  The  Diseases  of  Animals 1  50 

W.  H.  Jordan's  The  Feeding  of  Animals 1  50 

I.  P.  Roberts'  The  Horse 1  25 

M.  W.  Harper's  Breaking  and  Training  of  Horses 1  75 

George  C.  Watson's  Farm  P9ultry.     New  edition 1  50 

John  A.  Craig's  Sheep  Farming 1  50 

E.  F.  Phillips'  Beekeeping 2  00 

ON  DAIRY  WORK,  FARM  CHEMISTRY,  ETC. 

Henry  H.  Wing's  Milk  and  Its  Products.    New  edition  ....  1  50 

J.  G.  Lipman's  Bacteria  and  Country  Life 1  50 

ON  ECONOMICS  AND  ORGANIZATION 

William  A.  McKeever's  Farm  Boys  and  Girls 1  50 

I.  P.  Roberts'  The  Farmer's  Business  Handbook 1  25 

George  T.  Fairchild's  Rural  Wealth  and  Welfare 1  25 

H.  N.  Ogden's  Rural  Hygiene 1  50 

J.  Green's  Law  Tor  the  American  Farmer 1  50 

G.  H.  Powell's  Cooperation  in  Agriculture 1  50 

J.  B.  Morman's  Principles  of  Rural  Credits 1  25 


THE  MACMILLAN  COMPANY 

Publishers  64-66  Fifth  Avenue  ITew  Tork 


RURAL  TEXT- BOOK  SERIES 

Edited  by  L.  H.  BAILEY 
Each  volume  illustrated.  Cloth,  12mo* 


While  the  RURAL  SCIENCE  SERIES  is  designed  primarily  for 
popular  reading  and  for  general  use,  this  related  new  series  is  designed 
for  classroom  work  and  for  special  use  in  consultation  and  reference. 
The  RURAL  TEXT-BOOK  SERIES  is  planned  to  cover  eventually 
the  entire  range  of  public  school  and  college  texts. 

DUGGAR,  B.  M. 

Physiology  of  Plant  Production $1  60 

DUGGAR,  JOHN  FREDERICK 

Southern  Field  Crops 1  75 

GAY,  C.  WARREN 

Principles  and  Practice  of  Judging  Live-Stock     .      1  50 

HARPER,  M.  W. 

Animal  Husbandry  for  Schools 1  40 

HITCHCOCK,  A.  S. 

Grasses 1  50 

LIVINGSTON,  GEORGE 

Field  Crop  Production 1  40 

LTON,  T.  L.  AND  FIPPIN,  E.  O. 

Principles  of  Soil  Management 1  75 

MANN,  A.  R. 

Beginnings  in  Agriculture 75 

MONTGOMERY,  G.  F. 

Corn  Crops 1  60 

PIPER,  CHARLES  V. 

Forage  Plants  and  Their  Culture 1  75 

WARREN,  G.  F. 

Elements  of  Agriculture 1  10 

WARREN,  G.  F. 

Farm  Management 1  75 

WHEELER,  H.  J. 

Manures  and  Fertilizers 1  60 

WHITE,  EDWARD  A. 

Principles  of  Floriculture Preparing 

WIDTSOE,  JOHN  A. 

Principles  of  Irrigation  Practice 1  75 


THE   MACMILLAN  COMPANY 

Publishers  64-66  Fifth  Avenue  New  York 


The  Rural  Outlook  Set 

By  L.  H.  BAILEY 

Four  Volumes.  Each,  cloth,  12mo.   Uniform  binding,  attractively  boxed. 
$5.00       per  set;  carriage  extra.  Each  volume  also  sold  separately. 

In  this  set  are  included  three  of  Professor  Bailey's  most  popular  books 
as  well  as  a  hitherto  unpublished  one, — "The  Country-Life  Movement." 
The  long  and  persistent  demand  for  a  uniform  edition  of  these  Little 
classics  is  answered  with  the  publication  of  this  attractive  series. 

The  Country  Life  Movement 

Cloth,  I2mo,  220  pages,  $1.25         postage  extra 

This  hitherto  unpublished  volume  deals  with  the  present  movement 
for  the  redirection  of  rural  civilization,  discussing  the  real  country-life 
problem  as  distinguished  from  the  city  problem,  known  as  the  back-to-the- 
land  movement. 

The  Outlook  tO  Nature  (New  and  Revised  Edition) 

Cloth,  12mo,  195  pages,  $1.25         postage  extra 

In  this  alive  and  bracing  book,  full  of  suggestions  and  encouragement, 
Professor  Bailey  argues  the  importance  of  contact  with  nature,  a  sympa- 
thetic attitude  toward  which  "means  greater  efficiency,  hopefulness, 
and  repose." 

The  State  and  the  Farmer  (New  Edition) 

Cloth,  12mo,  $1.25         postage  extra 

It  is  the  relation  of  the  fanner  to  the  government  that  Professor 
Bailey  here  discusses  in  its  varying  aspects.  He  deals  specifically  with 
the  change  in  agricultural  methods,  in  the  shifting  of  the  geographical 
centers  of  farming  in  the  United  States,  and  in  the  growth  of  agricultural 
institutions. 

The  Nature  Study  Idea  (New  Edition) 

Cloth,  12mo,  $1.25         postage  extra 

"It  would  be  well,"  the  critic  of  The  Tribune  Farmer  once  wrote,  "if 
'The  Nature  Study  Idea'  were  in  the  hands  of  every  person  who  favors 
nature  study  in  the  public  schools,  of  every  one  who  is  opposed  to  it,  and 
most  important,  of  every  one  who  teaches  it  or  thinks  he  does."  It  has 
been  Professor  Bailey's  purpose  to  interpret  the  new  school  movement 
to  put  the  young  into  relation  and  sympathy  with  nature, — a  purpose 
which  he  has  admirably  accomplished. 


THE  MACMILLAN  COMPANY 

PUBLISHERS  64-66  Fifth  Avenue  NEW  YORK 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 

AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


YB   15725 


451825 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


